Proceedings of the Tomsk Technological Institute of Emperor Nicholas II.
Vol. XXVIII, 1912, No. 4.

Exhibition of Building Materials in Berlin.

V. F. Yuferev.

(Report on a business trip. 1 plate of drawings and 20 figures in the text).*

The 2nd exhibition of the clay, cement, and lime industries, of the building trade, and of fine ceramics in Berlin (Germany) in 1910 lasted from June 2 to July 18, new style.
(II Ton,—Zement— u. Kalkindustrie Ausstellung. Bauindustrie und Feinkeramik).

According to the charter of the German Society for the clay, cement, and lime industries, its aim is the technical improvement of the methods of producing those products manufactured by its members. At the beginning of the Society’s existence, in 1865, it fulfilled its task by means of reports and the discussion of questions raised at technical meetings. With the development of industry, new improved devices and new factories appeared, which prompted the members of the Society to resort to an annual collective inspection of new installations, both within the country and outside it; this practical way of enriching the members’ knowledge took root in the Society. Excursions are arranged annually in the summer.

After forty years of existence, the Union again expanded its activity and in 1905, in the premises of the Institute of Industrial Technology, organized the 1st exhibition for the clay and lime industries. Of course, in arranging the first exhibition there was no lack of doubts as to its necessity; however, the results of the exhibition proved brilliant, and the exhibition bureau received many orders for the exhibits. In short, the results of the exhibition were such that the Society came to the conclusion that exhibitions of this kind must be held regularly. The next exhibition was scheduled for 1910 in Berlin, where it also took place in the summer of last year.

572 firms took part in the exhibition, among them foreign ones as well.

During the exhibition the following reports were made:

1) June 9, “Zeitproblem der Architektur,” Geh. Regierungsrat. Hermann Muthesius.

*) Fig. (italic)—refers to the plate of drawings.

2) June 16, “Ueberblick über gesamte Materialprüfungswesen,” by Prof. M. Gary.

3) June 23, “Porzellan, mit besonderer Berücksichtigung des 200 jährigen Erfindungstages,” by Prof. Geh. Regierungsrath Heinike, director of the Royal Porcelain Manufactory.

4) June 30, “Gartenstädte,” by Dr. Wolf Dohrn.

5) July 7, “Friedhofskunst,” by Prof. Franz Seeck.

6) July 14, “Die Keramik im heutigen Kunstgewerbe,” by Prof. Dr. Georg Lehnert.

In addition, “Moderne Wohnungsheizung durch Kachelöfen,” by Kantor Gericke.

The exhibition occupied a large area that had not yet been built up, near a railway line. The area occupied by the exhibition was about 3–5 desyatinas. The main building (Fig. 1) was built of wood, covered with coarse canvas painted the color of light stone or stucco.

Fig. 1.

At present, opposite the entrance is the exhibition office; to the right of it is the department of machines and, to the left, products of ceramic manufacture. Behind the main building are pavilions, see the plan, of individual firms, or separate pavilions of associated firms.

In the right wing of the main building, attention was drawn first of all to the exhibition of works, instruments, and publications of the Royal Testing Station in Charlottenburg. To the right was a similar exhibition of the Tonindustrie-Laboratorium, Berlin,

Dreysestr. 4. In addition to the usual apparatus and products of its activity, the laboratory for the clay industry exhibited a new electric furnace for testing the fire resistance of materials, Fig. 2, in which the resistance is granular coke. Such a furnace was first introduced into use by the Charlottenburg testing station and was only improved by the laboratory of Prof. Seger and Kramer by the introduction of a through potassium channel and the corresponding placement of the whole furnace on a high tripod. These innovations created in the furnace a weak current of air, removing carbon monoxide and carbon dioxide formed from the coal and sometimes acting harmfully during experiments, and also simplified care of the furnace, since it became possible to introduce the substances being tested from below upward (through the lower opening) by means of a rising rod, Fig. 3.

Such a furnace has been acquired by the St. Petersburg ceramic laboratory (Prof. Sokolov) of the Technological Institute.

In this same section of the main pavilion are located the large machine-building firm for equipping cement and brick works, Smidth in Copenhagen, and the firm Karl Händle & Söhne, Mühlacker. A few words should be said about the exhibits of these two firms, since the machines displayed by the firms deserve this.

The firm Smidth draws attention with its box brick-making machine, designed for a large output of ordinary wall brick. The machine has a very great resemblance to its prototype—the Canadian machine. The improvement consists in the fact that all possible measures have been taken to reduce the expenditure of power on friction of its individual parts. Here there are also samples, both of green and of fired brick, manufactured by means of this machine. The material, clay, in its qualities, determined by means of the eyes and fingers, closely approaches the Tomsk and Novo-Nikolaevsk brick clays. Such a machine is capable of producing from 10,000 to 12,000 bricks of the Russian standard format (6×3×1½ vershoks) in 10 hours of work when operated by 2 adult workers and with an expenditure of 9 effective steam horsepower.

Further, the kominor exhibited by the same firm attracts the attention of every visitor to the exhibition and of the specialist by the neatness of its finish, its size, and the thoughtfulness of its design. The kominor, by its construction, is nothing other than an ordinary ball mill adapted for grinding cement clinker into the finest powder of finished Portland cement. The improvement introduced by the firm Smidth into the construction of kominors is the use of independent

of the grinding surface (separate from the mill drum itself) and the application of engineer Fasting’s patent, consisting in adapting to the kominor separate cylindrical sieves of small diameter, arranged around the circumference of the kominor, instead of the former one or two sieves, Fig. 4, enclosing it.

Fig. 4.

The construction of the new type of kominor and the distribution of forces in the material being sifted can be seen from Figures 4, 5, 6, 7.

and 8. In Fig. 5 the position of the material being crushed on the sieves is shown approximately as it actually occurs. The speed of the sieves reaches 3.35 meters per second. Owing to the high speed of the sieves, there is strong friction of the material being screened against their surface, the result of which is rapid wear of the sieve fabric. There is also a considerable loss of power, owing to the necessity of constantly raising the entire mass of the material being screened. Fasting’s design seeks to eliminate the enumerated shortcomings. Fig. 8 gives a diagram of the action of the forces in this design. Fasting, instead of one or two sieves with axes common to the axis of the crushing apparatus, introduced six separate sieves with

Fig. 6.

with axes parallel to the axis of the disintegrating apparatus and arranged around its circumference, as may be seen from Fig. 6. The material, falling onto the sieves, is distributed uniformly over the circumference of the mill drum, which produces an economy of power in rotating the whole device, while the speed of rotation of the sieves falls from 3.25 meters per second to 0.5 meter. In addition, with the new design easy access is possible to the outer disintegrating drum.

The arrangement of the disintegrating plate (surface) may be seen from Fig. 9.

Another firm, Karl Händler Söhne, Mühlacker, exhibited the complete equipment of a brickworks with an ordinary belt press, runners, and a mixing apparatus of special design. From the appended drawing 10 one can see the general arrangement of the machines in such equipment, and from Figs. 11 and 12 the construction of the mixing apparatus may be seen.

Work with this apparatus is carried out as follows: the raw material is brought directly to the mixer and dumped there, as may be seen from Fig. 12, each grade of material being thrown into the corresponding compartment, independent of the others.

Let compartment II be loaded with lean clay, and compartment I with fat clay. Belt conveyor c moves at a constant speed of about 0.20 m/min in the direction of the runners and carries with it the lower layer of compartment II, which has a gate e, by means of which the inflow of material from compartment II can easily be regulated by introducing one or another height of layer onto the conveyor, Fig. 11. The very same order of operation of the apparatus is maintained if a greater number of compartments is introduced; only the useful coefficient of performance of the apparatus changes.

By means of the tearing apparatus d, the layers of materials brought to it by the conveyor are torn into small pieces and, in this form, are fed to the disintegrating apparatus.

Depending on the properties of the materials, a moistener may be fitted to the apparatus. For an average output of 2–10 cubic meters of materials, the apparatus consumes from 1 to 2 effective horsepower.

In this same department there are many other exhibits of machine-building plants, but they either have no direct relation to the production of building materials, or, while having such a relation, have not exhibited anything more or less original in this respect.

Having passed through the machine department, we enter an area occupied by separate pavilions and individual plots with exhibi—

Exhibition of Building Materials in Berlin.

Fig. 10.

manufactured articles in the open air. Here, chiefly, are placed various products made of reinforced concrete and concrete. Beginning with the most utilitarian purposes, concrete and reinforced concrete rise to the purposes of serving artistic sculpture. It would have made the printing of the report too expensive to include in it photographs of the various reinforced-concrete and concrete products present at the exhibition, and therefore such photographs cannot find a place here.

Immediately upon leaving the right wing of the main pavilion (machines), we encounter the pavilion of Krupp and Wolf. Wolf’s locomotive sets Krupp’s machines in motion. This is an exhibition of already well-known machines. (Plan Nos. 311–312).

To the right of the exit (plan No. 544) is the pavilion of the machine-building works L. Schmelzer, Magdeburg. The firm has exhibited the complete equipment of a steam brickworks, all the machines being in operation, and the molded green brick being fed by an elevator back into the charging apparatus. The equipment is designed for ordinary brick clay and consists of:

1) A charging apparatus (Schmelzer system)

2) One pair of wet runners, 1200 × 350 cm, with a pierced plate.

3) Brick press 134.

4) A horizontal and inclined conveyor with self-acting lubrication.

5) A sand-spreading machine, in place of manual sprinkling.

6) The necessary transmission.

7) One 50 PS steam engine.

8) One Cornish boiler, 10 atm., 30 sq. m heating surface, with steam superheater.

The works has also exhibited a machine forming closed hollow bricks. The machine operates in place of the ordinary press. In this press the principle of Eng. W. Schelling has been realized. The press bears the name “Cella.”

The arrangement of the mouthpiece “Cella” is clearly visible from the appended Figure 13, and therefore there is no need for a special description of it.

During the operation of the machine, the clay is fed into the mouthpiece and, encountering the box \(H\), closed on one side by the slide \(S_2\), is pressed into the shape of a hollow prism; and when the slide \(S_2\) is raised and assumes position \(S_1\), the clay passes through the box \(H\) and forms the internal wall \(K\) in the endless hollow prism.

Leaving aside the description of exhibits of this kind by other factories, as having exhibited the usual types of machines and equipment for brickworks,—one should mention the returning

becoming a supply (and there has come to be a demand) for box presses.

The firm Schmelzer exhibited its press, which differs from the American (Canadian) ones in that the pressing of the clay into the mold—similar to the extrusion of a clay strip from a ribbon press—has been eliminated, and a new principle has been introduced for filling the mold (box) by pressing it into the clay mass lying above it. Before being introduced into the machine, the mold must be sprinkled with sand. According to the factory’s data, with an output of 1,500 pieces per hour of the German size, such a press consumes only 2 effective horsepower. The construction of the press can be seen from Fig. 15.

Presented chiefly were presses with boxes that feed the green brick from the machine automatically. Only one firm presented a type of box press, but with a movable table, Fig. 14; this was the firm C. Wulf, Wriezen. The hourly production—

Fig. 14.

the capacity of the press is equal to 1,500 bricks. The cost of the machine at the factory is 1,650 rubles.

The same firm also exhibited a further improvement of the very same Dornbusch—Bralitz patent, aimed at increasing the productivity of the machine, which in the press, Fig. 16, reaches 3,500 bricks per hour (German size). In this machine, as in the preceding one, the difference from the Canadian type consists in the elimination of boxes and in the introduction of a form (table) that remains with the machine, from which the molded brick is pressed out by a special stamp a, see Fig. 14. In the machine, Fig. 16, the green brick is pressed out onto carrier boards, which are brought under the stamp by means of two belt conveyors located on both sides of the machine.

Fig. 16.

The stamps are so successfully designed that, in the event that the mold becomes overfilled, or a stone accidentally gets into it, they do not press it into the mold but stop, thereby preserving both the mold and the stamp. I witnessed how the firm’s representative repeatedly placed his cane, made of light wood, under the stamp across the mold, and every time the stamp stopped, pressing only lightly on the cane. A great future may safely be predicted for these presses, since, with a low expenditure of power—from 1⅓ to 4 per 1,000 bricks of German size (whereas ordinary belt machines require 6–10 PS per 1,000 bricks)—they produce bricks for ordinary masonry whose structure is similar to that of hand-molded brick, and therefore,

therefore, of a quality superior to machine-made perforated brick.

In ordinary toggle presses one should note the designers’ tendency to eliminate the frequent lubrication of the teeth of the gear transmissions. In the “Kalypso” press, made by the firm Eduard Laeis & C-ie, Trier, this problem is solved by transferring all the gear transmissions to one part of the machine, giving them the smallest possible dimensions in all three measurements and covering them with tight casings; see Fig. 17.

Fig. 17.

The firm Roscher, Görlitz, solved the problem by introducing the smallest possible dimensions of gear wheels, made of the best steel, and, limiting the transmission to only a pair of them, enclosed them in an oil box, thereby achieving constant

lubrication of the teeth and a light, noiseless running of the machine. Thanks to this innovation, the consumption of power has been reduced. The factory guarantees a power consumption of \(2/3\) as compared with presses having ordinary transmission. According to the testimonials of two brickworks,*) which have installed these new machines, they confirm the data of the machine-building works.

In order to exhaust the novelties in the brickmaking field, it remains to mention clay-cleaners, chiefly for the admixture of limestone in lumps, and also the drying of the green brick.

The German Union for the clay, cement, and lime industries had already earlier turned its attention to the solution of this urgent question in brick technology—the question of neutralizing lime. On this subject, by commission of the Union, Dr. Möller presented a study. This study, highly valuable, reduces to the following conclusions:

1) When a firing temperature of from \(1050^\circ\) to \(1100^\circ\) is attained (Seger cone 05–08), the harmful action of marl is eliminated, and independently of its size.

2) At lower temperatures, washing out calcareous inclusions in the wet clay is the best means of rendering the lime harmless, since the bursting force of these inclusions on the brick rapidly falls as their dimensions diminish.

However, the first point does not yet make it possible to judge, for the given clay and the admixture of lime (marl) in it, how it will behave even when fired at \(1050^\circ\)–\(1100^\circ\) C. The study was not extended to a large number of clays, and the quantity of the remaining free lime (not silicate) is not given. As regards the second point: it remains to investigate what should be the greatest size of grain and what should be the greatest number of grains per unit volume of brick, so that, at firing temperatures lower than \(1050\)–\(1100\) C., the lime would not exert a destructive action on the fired brick.

Fig. 18.

A sharp decline

*) G. m. b. H. Jos. Hergel i. Ullersdorf b. Naumburg a. Qu. u. Oswald Mielke, Liegnitz.

Fig. 18.

The relation between the tearing force of the fired piece of lime and the decrease in its dimensions has long attracted the attention of designers of machines for processing clay.

At the exhibition there was shown in operation the Bonn clay cleaner, Fig. 18, built on the principle of a horizontal belt press, in which the mouthpiece is replaced by a stone catcher, and the part of the drum in front of the mouthpiece is replaced by a perforated surface. Such an apparatus is at present already in operation at many brickworks in Germany. Clay cleaners are built on the same principle by the firm Ed. Laeis & C-ie, Trier, Fig. 19. This machine bears the name “Puro.”

A considerable improvement of the clay cleaner is represented by Bauer’s patent, Fig. 20, unfortunately not shown at the exhibition. Fig. 20 represents the working surface of the rolls and a slotted steel plate that squeezes the clay paste through the slots and thus frees the paste from stony inclusions.

It remains also to mention one not shown at the exhibition

although there is also a new mould for the manufacture of wedge-shaped bricks for vaults. The idea of the mould is so simple that it is fully intelligible from the accompanying drawing, Fig. 23. The drawing shows a transverse section of the mould, with, with the wire tape cutting lengthwise. The surface of the receiving table must, of course, correspond to the lower surface of the tape. F. Heilscher sees the following advantages in the manufacture of wedge-shaped bricks by means of the mould described:

Fig. 20

1) During drying, only the wide (upper) side of the clay, on which it is placed for drying, is somewhat damaged.

2) During drying the green brick occupies very little space.

3) Great productivity with the former moisture content of the raw material, about 30%.

Also presented at the exhibition was a new transmission of power by means of steel bands. It works well, quite noiselessly, but on machines running idle. Steel bands—belts—save power, but, despite this, in brick, cement, lime, and other works, in general in the technology of building materials, they are not applicable because they tear easily when the load changes considerably or in the presence of damp dust. It is enough for a small spot of rust to form, and the steel belt will necessarily break. A further great inconvenience of such transmission is that it must be well guarded, since otherwise the band, when it breaks at any appreciable speed, cuts to pieces everything it meets in its flight. For electrical installations in premises where there is no dust and at high belt speeds, steel belts—bands—render good service, as indeed they do generally wherever there is a constant load and a clean room for the machines.

The question of drying brick yielded almost nothing new, unless one counts certain improvements to patents that have already existed for a long time.

The general tendency of all designers of dryers is directed toward making the fullest possible use of the heat lost during firing.

The dryer presented by the Smidth works is distinguished by the most original heating arrangement. The innovation consists in adding radiators, Fig. 24, to the old, well-known dryer of this firm.

Water flows through the radiators, heated by exhaust steam to 90–95° C. At night, when the machine is not operating, the water has time to cool to 60°–70° C.

This system has found application in many works in Denmark, Germany, Sweden, and Finland. The advantage of this system is that the water heating operates quite automatically, and a temperature of 15°–20° C is easily maintained in the dryers.

One cannot pass over in silence the dryers of the “Construction Company for Dryers.” The channel dryers of this company enjoy particular success. The dryers themselves are of a commonly known type, improved by the introduction of steam heating and special small cars, which permit the automatic loading and unloading of the green material. The success of these dryers may be seen from the data on their construction:

Year	In production
1905	400 meters of channel
1906	800 meters of channel
1907	1400 meters of channel
1909	6200 meters of channel

As for novelties in the construction of ceramic kilns, here, properly speaking, nothing new has been created; on the contrary, a return to the old is noticeable. The firm Eckardt & Hotop has taken out a patent for a grate-fired annular kiln; the grates (fireboxes) are placed on both sides of the channel, i.e., the kiln is widened across its width for the convenience of firing it, Fig. 25. One such kiln has been built in Hungary at the large lime works in Felsőgalla.

The second novelty—the patent of H. Becker, jun.: “Reformringofensystem Renard”—is distinguished by the introduction of serpentine channels under the floor of the kiln. The purpose of the channels is to preheat the underside of the kiln in the chambers before the fire is lit, and to bring the heated air under the hotplates for loading coal through the kiln floor (grates) for better combustion of the coke that is formed. This is, in fact, the idea of Hoffmann himself, which he implemented in his first kiln, still operating at the present time near Breslau. In later constructions of his kiln, Hoffmann eliminated the channel as superfluous.

Among the buildings and pavilions of the exhibition, a Roman villa, Fig. 21, built from—

Fig. 21.

by the joint society for the clay, cement, and lime industries, according to the design of Prof. O. Stiehl.

The pavilion of the two united societies of cement manufacturers of Germany and manufacturers of cement goods; Fig. 22,

Fig. 22.

shows the view of the main entrance to the pavilion; Fig. 23—the inner courtyard with a basin, the side passages, and the glazed part

Fig. 26.

of the pavilion, the hall in which are placed the implements of production and all the means for making Portland cement—everything, of course, presented on a small scale and partly in drawings, partly in models. The entire building is made of concrete and reinforced concrete.

One cannot pass over in silence, either, the pavilion erected by the manufacturers of the Lower Alsatian clay industry. The building is of concrete and reinforced concrete; the decorations are ceramic, Fig. 27.

Fig. 27.

As for artistic ceramics, the leading role in this respect at the exhibition is played by the Prussian Royal Porcelain Manufactory.

There are, at least among the principal ones, two trends in the technique of artistic ceramics: the art of applying underglaze designs, and figure modeling.

The art of rendering artistic pictures with underglaze paints seeks to combine the tones available to the artist into a harmonious whole; and this is not so easy, since the number of underglaze paints is very limited. Since the number of colors has now increased by two—yellow and yellow-brown—these tones distinguish the Prussian Royal Manufactory.

Underglaze coloring recalls lithography in three and four colors. The simplest motifs are conveyed very successfully, but the more variegated colored pictures still leave much to be desired in the technique of execution.

Figure modeling is successful; for example, this may be seen in Fig. 28. The figure of Flora, the work of Prof. Schlei, or the pair of elephants in Fig. 29.

The same may be said also of another first-rate manufactory, which likewise serves, like the first, as a model for numerous German manufacturers: the famous Meissen Porcelain Manufactory. Here, however, a greater number of tones predominates.

Of the colored modeling, the figure of a mother-of-pearl rooster with a hen, by Paul Walter, is of interest. Their pose is very natural, which is why this group attracts attention, Fig. 30.

Fig. 28.

A not poor rendering of the design is distinguished—

... and the figure of a shepherd with sheep, Fig. 31, executed by Heutscheel.

In a small hut built of Rüdersdorf limestone on cement mortar, the exhibition of the Royal Mining Inspectorate in Rüdersdorf is housed.

The famous Rüdersdorf limestone quarries are under the jurisdiction of the inspectorate.

Stone is quarried by blasting operations; at one time a layer 30 meters high is blasted, which yields about 10,000 cubic sazhen of stone.

Limestone is burned chiefly in a ring kiln, the largest in Germany; the capacity of this kiln, under normal operation, is 200 tons ≃ 12,500 poods per day, and under intensified operation—250 tons ≃ 15,600 poods per day. In addition to the Hoffmann kiln, there are also old shaft kilns, 18 in number, each with a capacity of 15 tons ≃ 935 poods per day.

Fig. 29.

Fig. 30.

Fig. 31.

The production employs 1,050 workers with 20 persons of senior staff.

The output of the plant and quarries:

58,700,000 poods per year of stone,
3,750,000 ” ” of quicklime.

The waste product of production—crushed stone, in sizes from 2 to 20 mm and from 20 to 40 mm, washed—is sold for the manufacture of concrete; concrete prepared with such washed crushed stone has considerable resistance to crushing, as may be seen from the table placed on p. 21.

An exceedingly interesting spectacle is presented by the appearance of the extensive sand-lime (brick) building. The Union of manufacturers of sand-lime brick (silicate brick) set itself the task of tracing the effect of the high temperature of a fire on the fire resistance of their product; that is, whether silicate brick is equal in endurance to clay brick at fire temperatures; whether silicate brick can serve not only as ordinary wall brick, but also as facing brick.

On April 25, N.S., 1910, under the direction of the Royal—

No.	Age of specimen	Composition	Resistance to crushing
1	8 days 28 ”	100 cement 120 sand 230 crushed stone (2–20 mm)	215 298
2	8 ” 28 ”	100 cement 150 sand 350 crushed stone (2–20 mm)	188 265
3	8 ” 28 ”	100 cement 180 sand 420 crushed stone (2–20 mm)	149 222
4	8 ” 28 ”	100 cement 200 sand 200 crushed stone (20–40 mm)	262 350
5	8 ” 28 ”	100 cement 250 sand 250 crushed stone (20–40 mm)	192 278
6	8 ” 28 ”	100 cement 300 sand 300 crushed stone (20–40 mm)	169 245

…Prussian testing station for materials, an artificial fire was produced in a building of sand-lime brick, built according to the design of Prof. Peter Behrens, Neubabelsberg. Figs. 32, 35–37 give a picture of the fire and of the architecture of the building. In Fig. 33 one can see the effect of the fire on various bricks. Under the sign Z is clay brick; under the remaining signs, sand-lime brick from various factories.

The results of the test, speaking modestly, showed that properly prepared sand-lime silicate brick is in no way inferior to ordinary clay brick as a fire-resistant building material.

In view of the low cost of producing silicate brick, its handsome appearance, and its strength, its spread in Russia would be desirable; however, for this an initiative on the part of government institutions is necessary, in order to show the advantage and safety of using the new material. The governments of Germany and France took the initiative in this direction many years ago. Germany used the new material for the construction of barracks buildings, and France for marine structures.

What, then, has the exhibition of the clay, cement, and lime industry in Germany yielded?

The exhibition presented a complete picture of the triumphal progress, over this five-year period, 1905–1910, of the sciences connected with artistic ceramics and the technology of building materials (binding mortars and artificial stones).

Fig. 32.

The long-standing doctrine of the plasticity of clays, which has interested specialists for so long, acquired new light. The patent of Acheson D. R. P. 153513, for the preparation of a clay mass of greater plasticity by mixing it with tannin and other substances, prompted the study of the very process of the aging of clays, as is attested by the works of F. Koerner, Keppeler, and Spongenberg. R. Rohland seeks to explain this same question on the basis of the doctrine of dissociation. Zschokke¹ worked much on resolving the question of the plasticity of clays; however, his attempt to draw any conclusions from the rich factual material he had collected did not succeed. Zschokke makes the essence of plasticity dependent on the colloids contained in the clay. Hugo Hermann² adopted the same point of view.

The practical results of the investigations are as follows: from non-plastic quartz and a very small quantity of plastic kaolin, mixed with non-plastic feldspar, there is obtained a very plastic and easily worked porcelain body.

Fig. 33.

The very method of working with the clay mass has also undergone a considerable change. The effect of acids and alkalis on the plasticity of clays had long been known,¹ and this was used to obtain clay cast products; now, by this route, it has become possible to prepare such bulky products as, for example, pots for melting glass.²

The necessity of measuring high temperatures has several times, during the past period, compelled verification of the melting temperatures of Seger cones.

¹ Seger’s gesammelte Schriften.

² E. Weber, “Die Herstellung v. glashäfen durch giessen,” Sprechsaal, 1905. Dr. M. Simonis, ibid., 1705, 1906.

In corrected form, the previous table of Seger cones and their composition will be as follows.

Cone No.	Chemical formula	Composition	Probable melting temperature
1*	$\left.\begin{array}{l}0{,}3\,K_2O\\0{,}7\,CaO\end{array}\right\}\left.\begin{array}{l}0{,}2\,Fe_2O_3\\0{,}3\,Al_2O_3\end{array}\right\}4SiO_2$	Feldspar — 83,55 Marble — 35,00 Quartz — 66,00 Iron oxide — 16,00	1a — 1100° * These pyramids, replacing the new 1a–6a, are set at the corresponding temperatures.
2*	$\left.\begin{array}{l}0{,}3\,K_2O\\0{,}7\,CaO\end{array}\right\}\left.\begin{array}{l}0{,}1\,Fe_2O_3\\0{,}4\,Al_2O_3\end{array}\right\}4SiO_2$	Feldspar — 83,55 Marble — 35,00 Quartz — 60,00 Iron oxide — 8,00 Zettlitz kaolin — 12,95	Difference $-0{,}05\,Fe_2O_3 + 0{,}05\,Al_2O_3$ 2a — 1120° * These pyramids, replacing the new 1a–6a, are set at the corresponding temperatures.
3*	$\left.\begin{array}{l}0{,}3\,K_2O\\0{,}7\,CaO\end{array}\right\}\left.\begin{array}{l}0{,}05\,Fe_2O_3\\0{,}45\,Al_2O_3\end{array}\right\}4SiO_2$	Feldspar — 83,55 Marble — 35,00 Quartz — 57,00 Iron oxide — 4,00 Zettlitz kaolin — 19,43	Difference $-0{,}05\,Fe_2O_3 + 0{,}05\,Al_2O_3$ 3a — 1140° * These pyramids, replacing the new 1a–6a, are set at the corresponding temperatures.
4*	$\left.\begin{array}{l}0{,}3\,K_2O\\0{,}7\,CaO\end{array}\right\}0{,}5\,Al_2O_3.4SiO_2$	Feldspar — 83,55 Marble — 35,00 Quartz — 54,00 Zettlitz kaolin — 25,90	4a — 1160° * These pyramids, replacing the new 1a–6a, are set at the corresponding temperatures.
5*	$\left.\begin{array}{l}0{,}3\,K_2O\\0{,}7\,CaO\end{array}\right\}0{,}5\,Al_2O_3.5SiO_2$	Feldspar — 83,55 Marble — 35,00 Quartz — 84,00 Zettlitz kaolin — 25,90	5a — 1180° * These pyramids, replacing the new 1a–6a, are set at the corresponding temperatures.
6*	$\left.\begin{array}{l}0{,}3\,K_2O\\0{,}7\,CaO\end{array}\right\}0{,}6\,Al_2O_3.6SiO_2$	Feldspar — 83,55 Marble — 35,00 Quartz — 108,00 Zettlitz kaolin — 38,85	6a — 1200° * These pyramids, replacing the new 1a–6a, are set at the corresponding temperatures.
7	$\left.\begin{array}{l}0{,}3\,K_2O\\0{,}7\,CaO\end{array}\right\}0{,}7\,Al_2O_3.7SiO_2$	Feldspar — 83,55 Marble — 35,00 Quartz — 132,00 Zettlitz kaolin — 51,80	Difference $0{,}1\,Al_2O_3 + 1\,SiO_2$ — 1230°
8	$\left.\begin{array}{l}0{,}3\,K_2O\\0{,}7\,CaO\end{array}\right\}0{,}8\,Al_2O_3.8SiO_2$	Feldspar — 83,55 Marble — 35,00 Quartz — 156,00 Zettlitz kaolin — 64,75	Difference $0{,}1\,Al_2O_3 + 1\,SiO_2$ — 1250°

No. of pyramid	Chemical formula	Composition	Probable melting temperature
9	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,0.9\,Al_2O_3.9SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 180.00 Tsetlitz kaolin 77.70	Difference $0.1\,Al_2O_3 + 1SiO_2$ 1280°
10	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,1.0Al_2O_3.10SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 204.00 Tsetlitz kaolin 90.65	Difference $0.1\,Al_2O_3 + 1SiO_2$ 1300°
11	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,1.2Al_2O_3.12SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 252.00 Tsetlitz kaolin 116.55	Difference $0.2\,Al_2O_3 + 2SiO_2$ 1320°
12	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,1.4\,Al_2O_3.14SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 300.00 Tsetlitz kaolin 142.45	Difference $0.2\,Al_2O_3 + 2SiO_2$ 1350°
13	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,1.6\,Al_2O_3.16SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 348.00 Tsetlitz kaolin 168.35	Difference $0.2\,Al_2O_3 + 2SiO_2$ 1380°
14	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,1.8\,Al_2O_3.18SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 396.00 Tsetlitz kaolin 194.25	Difference $0.2\,Al_2O_3 + 2SiO_2$ 1410°
15	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,2.1\,Al_2O_3.21SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 468.00 Tsetlitz kaolin 233.10	Difference $0.3\,Al_2O_3 + 3SiO_2$ 1435°
16	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,2.4\,Al_2O_3.24SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 540.00 Tsetlitz kaolin 271.95	Difference $0.3\,Al_2O_3 + 3SiO_2$ 1460°
17	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,2.7\,Al_2O_3.27SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 612.00 Tsetlitz kaolin 310.80	Difference $0.3\,Al_2O_3 + 3SiO_2$ 1480°

Brick No.	Chemical formula	Composition	Note	Probable melting temperature
18	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,3.1\,Al_2O_3.31SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 708.00 Zettlitz kaolin 362.60	$Al_2O_3+4SiO_2$	1500°
19	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,3.5\,Al_2O_3.35SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 804.00 Zettlitz kaolin 414.40	Difference $0.4\,Al_2O_3+4SiO_2$	1520°
20	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,3.9\,Al_2O_3.39SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 900.00 Zettlitz kaolin 466.20	Difference $0.4\,Al_2O_3+4SiO_2$	1530°
21	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,4.4\,Al_2O_3.44SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 1020.00 Zettlitz kaolin 530.95	Difference $0.5\,Al_2O_3+55SiO_2$; not manufactured	1548°
22	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,4.9\,Al_2O_3.49SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 1140.00 Zettlitz kaolin 595.70	Difference $0.5\,Al_2O_3+55SiO_2$; not manufactured	1550°
23	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,5.4\,Al_2O_3.54SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 1260.00 Zettlitz kaolin 660.45	Difference $0.5\,Al_2O_3+55SiO_2$; not manufactured	1555°
24	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,6\,Al_2O_3.60SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 1404.00 Zettlitz kaolin 738.15	Difference $0.6\,Al_2O_3+6SiO_2$; bricks 21, 22, 23, 24 and 25 are more than not manufactured	1560°
25	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,6.6\,Al_2O_3.66SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 1548.00 Zettlitz kaolin 815.85	Difference $0.6\,Al_2O_3+6SiO_2$; bricks 21, 22, 23, 24 and 25 are more than not manufactured	1566°
26	$\left.\begin{array}{l}0.3\,K_2O\\0.7\,CaO\end{array}\right\}\,7.2\,Al_2O_3.72SiO_2$	Feldspar 83.55 Marble 35.00 Quartz 1692.00 Zettlitz kaolin 893.55	Difference $0.6\,Al_2O_3+6SiO_2$; bricks 21, 22, 23, 24 and 25 are more than not manufactured	1580°

No. of pyramid	Chemical formula	Composition	Probable melting temperature
27	$0{,}3\,K_2O\left.\begin{array}{l} \\ \end{array}\right\}20Al_2O_3.200SiO_2$ $0{,}7\,CaO\left.\begin{array}{l} \\ \end{array}\right\}$	Feldspar — 83,55 Marble — 35,00 Quartz — 4764,00 Zettlitz kaolin — 2551,13	1610°
28	$Al_2O_3.10SiO_2$	Quartz — 240,00 Zettlitz kaolin — 129,50 Difference — $2SiO_2$	1630°
29	$Al_2O_3.8SiO_2$	Quartz — 180,00 Zettlitz kaolin — 129,50 Difference — $2SiO_2$	1650°
30	$Al_2O_3.6SiO_2$	Quartz — 120,00 Zettlitz kaolin — 129,50 Difference — $2SiO_2$	1670°
31	$Al_2O_3.5SiO_2$	Quartz — 90,00 Zettlitz kaolin — 129,50 Difference — $1SiO_2$	1690°
32	$Al_2O_3.4SiO_2$	Quartz — 60,00 Zettlitz kaolin — 129,50 Difference — $1SiO_2$	1710°
33	$Al_2O_3.3SiO_2$	Quartz — 30,00 Zettlitz kaolin — 129,50	1730°
34	$Al_2O_3.2{,}5SiO_2$	Quartz — 15,00 Zettlitz kaolin — 129,50	1750°
35	$Al_2O_3.2SiO_2$	Zettlitz kaolin	1770°
36*	$Al_2O_3.1{,}66SiO_2$	Grünstädter k. — 259,00 Calcined alumina — 20,60	1790°
37*	$Al_2O_3.1{,}33SiO_2$	Grünstädter k. — 259,00 Calcined alumina — 51,50	1825°
38*	$Al_2O_3.1SiO_2$	Grünstädter k. — 259,00 Calcined alumina — 103,00	1850°
39*	$Al_2O_3.0{,}66SiO_2$		1880°

Cone No.	Chemical formula	Composition	Probable melting temperature
40*	$\mathrm{Al_2O_3\cdot 0{,}33SiO_2}$		1920°
41*	$\mathrm{Al_2O_3\cdot 0{,}13SiO_2}$		1960°
42*	$\mathrm{Al_2O_3}$		2000°

Dr. Simonis, in Sprechsaal 1908, No. 41, noting the unfavorable effect of a reducing flame in ceramic kilns on Seger cones, replaced the lead-containing numbers with ones free of it, retaining only the most readily fusible number in its former form:

No.	Composition	Melting temperature
022	$\begin{aligned}0{,}5\,\mathrm{Na_2O}\\0{,}5\,\mathrm{PbO}\end{aligned}\left\{\begin{aligned}2\mathrm{SiO_2}\\1\mathrm{B_2O_3}\end{aligned}\right.$	600°
021	$\begin{aligned}0{,}5\,\mathrm{Na_2O}\\0{,}25\,\mathrm{CaO}\\0{,}25\,\mathrm{MgO}\end{aligned}\left\}\;0{,}02\,\mathrm{Al_2O_3}\;\left\{\begin{aligned}1{,}04\mathrm{SiO_2}\\1{,}0\mathrm{B_2O_3}\end{aligned}\right.$	650°
020	$\begin{aligned}0{,}5\,\mathrm{Na_2O}\\0{,}25\,\mathrm{CaO}\\0{,}25\,\mathrm{MgO}\end{aligned}\left\}\;0{,}04\,\mathrm{Al_2O_3}\;\left\{\begin{aligned}1{,}08\mathrm{SiO_2}\\1\mathrm{B_2O_3}\end{aligned}\right.$	670°
019	$\begin{aligned}0{,}5\,\mathrm{Na_2O}\\0{,}25\,\mathrm{CaO}\\0{,}25\,\mathrm{MgO}\end{aligned}\left\}\;0{,}08\,\mathrm{Al_2O_3}\;\left\{\begin{aligned}1{,}16\mathrm{SiO_2}\\1\mathrm{B_2O_3}\end{aligned}\right.$	690°
018	$\begin{aligned}0{,}5\,\mathrm{Na_2O}\\0{,}25\,\mathrm{CaO}\\0{,}25\,\mathrm{MgO}\end{aligned}\left\}\;0{,}13\,\mathrm{Al_2O_3}\;\left\{\begin{aligned}1{,}26\mathrm{SiO_2}\\1{,}0\mathrm{B_2O_3}\end{aligned}\right.$	710°
017	$\begin{aligned}0{,}5\,\mathrm{Na_2O}\\0{,}25\,\mathrm{CaO}\\0{,}25\,\mathrm{MgO}\end{aligned}\left\}\;0{,}2\,\mathrm{Al_2O_3}\;\left\{\begin{aligned}1{,}4\mathrm{SiO_2}\\1{,}0\mathrm{B_2O_3}\end{aligned}\right.$	730°
016	$\begin{aligned}0{,}5\,\mathrm{Na_2O}\\0{,}25\,\mathrm{CaO}\\0{,}25\,\mathrm{MgO}\end{aligned}\left\}\;0{,}31\,\mathrm{Al_2O_3}\;\left\{\begin{aligned}1{,}61\mathrm{SiO_2}\\1\mathrm{B_2O_3}\end{aligned}\right.$	750°

*) Cones 36 and 37 were introduced by Hecht; cones 38 to 42 were introduced by Marquardt. Seger’s No. 36 was prepared from shell-bearing clayey sandstone.

Melting temperature

\[ \begin{array}{r l} 015& \left. \begin{array}{l} 0{,}432\,\mathrm{Na_2O}\\ 0{,}432\,\mathrm{CaO}\\ 0{,}136\,\mathrm{MgO} \end{array} \right\} \;0{,}34\,\mathrm{Al_2O_3}\; \left\{ \begin{array}{l} 2{,}06\,\mathrm{SiO_2}\\ 0{,}86\,\mathrm{B_2O_3} \end{array} \right. \qquad 790^\circ \\[1.2em] 014& \left. \begin{array}{l} 0{,}385\,\mathrm{Na_2O}\\ 0{,}385\,\mathrm{CaO}\\ 0{,}230\,\mathrm{MgO} \end{array} \right\} \;0{,}34\,\mathrm{Al_2O_3}\; \left\{ \begin{array}{l} 1{,}92\,\mathrm{SiO_2}\\ 0{,}77\,\mathrm{B_2O_3} \end{array} \right. \qquad 815^\circ \\[1.2em] 013& \left. \begin{array}{l} 0{,}343\,\mathrm{Na_2O}\\ 0{,}343\,\mathrm{CaO}\\ 0{,}314\,\mathrm{MgO} \end{array} \right\} \;0{,}34\,\mathrm{Al_2O_3}\; \left\{ \begin{array}{l} 1{,}78\,\mathrm{SiO_2}\\ 0{,}69\,\mathrm{B_2O_3} \end{array} \right. \qquad 835^\circ \\[1.2em] 012& \left. \begin{array}{l} 0{,}345\,\mathrm{Na_2O}\\ 0{,}341\,\mathrm{CaO}\\ 0{,}314\,\mathrm{MgO} \end{array} \right\} \;0{,}365\,\mathrm{Al_2O_3}\; \left\{ \begin{array}{l} 2{,}04\,\mathrm{SiO_2}\\ 0{,}68\,\mathrm{B_2O_3} \end{array} \right. \qquad 855^\circ \\[1.2em] 011& \left. \begin{array}{l} 0{,}349\,\mathrm{Na_2O}\\ 0{,}340\,\mathrm{CaO}\\ 0{,}311\,\mathrm{MgO} \end{array} \right\} \;0{,}4\,\mathrm{Al_2O_3}\; \left\{ \begin{array}{l} 2{,}38\,\mathrm{SiO_2}\\ 0{,}68\,\mathrm{B_2O_3} \end{array} \right. \qquad 880^\circ \end{array} \]

The little pyramids containing iron were replaced by Simonis with pyramids composed of the mass of the former pyramid No. 7 with the addition of magnesite mixture \([33{,}5\% \text{ kaolin} + 56{,}5\% \mathrm{Nz}\ 7,\)

\[ \text{of composition }\left( \begin{array}{l} 0{,}5\,\mathrm{Na_2O}\\ 0{,}5\,\mathrm{CaO} \end{array} \right\} \;0{,}2\,\mathrm{Al_2O_3}\; \left\{ \begin{array}{l} 2\,\mathrm{Si_2O}\\ 1\,\mathrm{B_2O_3} \end{array} \right),\ \text{and }10\%\text{ magnesite}]. \]

The composition of the new little pyramids is as follows:

No.	Weight parts of pyramid No. 7	Weight parts of magnesite mixture	Composition Nz.	Tsetlitsky kaolin	Magnesite	Quartz	Feldspar	Melting temperature
6a	98	2
5a	95,5	4,5
4a	93	7
3a	90	10
2a	85	15
1a	80	20
01a	74	26						1080°
02a	68	32						1060°
03a	61	39						1040°
04a	54	46						1020°
05a	45	55						1000°
06a	38	62						980°
07a	32	68						960°
08a	23	77						940°
09a			50,4	22,8	7,2	16,8	2,8	920°
010a			56	22	8	12	2	900°

Iron-containing pyramids that did not contain it were replaced on the same grounds as lead-containing ones.

At present, only the undisputed right remains for Zeger cones to be used in ceramic production, but not for scientific investigations.

In view of the great importance of the coefficient of thermal conductivity for stone materials at high temperatures, work in this direction was carried out by S. Vologdin in the Le Chatelier laboratory. Table of thermal conductivity of stone materials at \(1000^\circ\) inside the furnace.

Material	Quantity of gram-calories through 1 sq. cm and 1 centimeter of thickness
Ordinary brick, not refractory	0.0037
Red brick	0.0029
another sort	0.0035
Refractory clay, fired at \(1000^\circ\)	0.0030
Refractory luting	0.0031
” ” ” ”	0.0035
Retort material	0.0040
Tubs for glass melting, fired at \(1200^\circ\)	0.0026
” ” ” ” ” \(1600^\circ\)	0.0047
Bauxite	0.0030
Dinas brick, fired at Zeger cone No. 9.	0.0033
at lower temperatures	0.0019
Magnesia	0.0058
Chrome iron ore	0.0054
Graphite	0.0145
Carborundum	0.0150

The electrical conductivity of insulating porcelain was tested. A. S. Watt (Transact. Americ. Ceramic Soc. Vol. 9 p. 600, according to Bonny, p. 52) worked out the following rules for insulating porcelain:

The required firing temperature rises with the content of lime in the porcelain body and falls in the presence of potassium. The resistance to current is highest with good firing; with still stronger firing it remains for the most part likewise high, but with weak, insufficient firing it falls considerably lower. Zoellner confirmed these rules (Electrot. Zeitschr. S. 1257, according to Bonny, p. 52) and indicated the necessary firing temperature of \(1400—1450^\circ\) C., and the intensifying influence of air bubbles in the porcelain body on its electrical conductivity.

The accessibility of electric current has brought about wide applica-

…its use for experimental furnaces; the most interesting furnace for determining the high temperatures of ceramic and glass manufacture has been described above: the furnace of the Tonindustrie-Laboratorium of Prof. Seger and Cramer in Berlin.

As is well known, on the basis of elementary chemical analysis alone it is impossible to judge the refractoriness of ceramic compositions. This circumstance gave rise to the rational analysis of clays.

The investigations of Bischof, Richter, and Seger established the following fundamental propositions:

1) “The chemical process of the melting of clays consists in the formation of double silicates, the fusibility of which increases with an increase in the content of silicic acid. If a clay melts in the heat of our furnaces, then it is necessary to assume in it the presence of a certain quantity of fluxes, since pure silicate of alumina (i.e. $Al_2O_3 . 2SiO_2$) does not melt.” Bischof.

2) “The degree of refractoriness of clays depends on the ratio of fluxes to the refractory constituent parts—silica and alumina.

The refractoriness of clays depends for the most part on the presence of magnesia, after which, it should be noted, come ferric oxide and, lastly, potash.

This proposition was supported by Richter with numerous experiments. The method itself for conducting the analysis was developed by A. E. Sabek.

The fundamental propositions cited served as a guiding star for further work on the study of the relation between the composition and fusibility of substances and mixtures.

The system alumina—silica was studied by Seger, who also drew up a melting diagram. Boudouard determined the melting temperature of the system lime—silica with the aid of Seger cones. Mixtures with a lime content of 30–90% melt below 1500° C. The experiments of Rieke (Sprechsaal 1907, No. 44) show that mixtures rich in lime melt considerably with greater difficulty.

Composition	$2CaO$ $SiO_2$	$CaO$ $SiO_2$	$2CaO$ $3SiO_2$	$CaO$ $2SiO_2$	$2CaO$ $5SiO_2$	$CaO$ $3SiO_2$	$CaO$ $6SiO_2$	$SiO_2$
by Boudouard	16–17	15–16	14–15	16	21–26	31	32–33	35
Rieke	29	19	15	15	20–26	29	32–33	36

H. Philippi (Ing. Diss.) found that the Rieke values for lime-rich compositions are very small. The results of Philippi’s tests:

	Seger cones	Wanner pyrometer
Trisilicate \((2\ \mathrm{CaO},\ 3\ \mathrm{SiO}_2)\)	14	1410—1420°
Bisilicate \((\mathrm{CaO},\ \mathrm{SiO}_2)\)	17—18	1490—1500°
\((4\ \mathrm{CaO},\ 3\ \mathrm{SiO}_2)\)	16	1450°
\((2\ \mathrm{CaO},\ \mathrm{SiO}_2)\), on cooling, disintegrate	40	1920—1930°
\((3\ \mathrm{CaO},\ \mathrm{SiO}_2)\), on cooling, disintegrate	41	1960—1970°

Experiments carried out by Arthur Day with the participation of Allen, Shepherd, White, and Wright at the Carnegie Institution gave average results for silicates with a lime content:

Percentage content of CaO:	30,	32,	35,	40,	45,	48.2,	50,	52,	54,
Melting temperature in degrees	1420,	1418,	1418,	1437,	1456,	1512,	1470,	1457,	1433,
Percentage content of CaO:	55.5	57,	60,	62.5	65	67.5.
Melting temperature in degrees	1466,	1431,	1426,	1429,	2082,	2015.

Experiments on the influence of lime on kaolin (the fusibility of mixtures) were carried out by Kramer (Tonind—Z. 1903, S. 1679); later, R. Rieke (Sprechsaal 1906, S. 1295) studied the influence of magnesia on the porosity and refractoriness of clays.

C. W. Parmelee (Sprechsaal 1907, S. 693) studied the influence of phosphoric acid on ceramic bodies. The influence of titanic acid on silica, alumina, and kaolin was studied by Rieke (Sprechsaal 1908, S. 405). On silica and kaolin, titanic acid has an effect, lowering their melting temperature by 100° with a 10% addition of titanic acid, and by 200°—300° with a 20% addition.

M. Theusner engaged in determining the melting temperature of lime–alumina silicates; the following melting temperatures were found by him:

	I	II	III	IV	V	VI	VII	VIII	IX
% \(\mathrm{Al}_2\ \mathrm{O}_3\)	60	60	60	30	20	10	30	20	10
\(\mathrm{SiO}_2\)	10	20	30	60	60	60	10	20	30
\(\mathrm{CaO}\)	30	20	10	10	20	30	60	60	60
T-ra C°	1400	1500	1600	1450	1300 to 1325	1400	1400 to 1425	1450 to 1475	1650

The application of scientific knowledge obtained is gradually causing the methods of factory practice to change as well.

Not so long ago, technicians engaged in furnace construction were especially concerned with using materials to obtain the greatest possible refractoriness. At the present time refractoriness has been pushed aside, and a new requirement has come to the fore—the ability to withstand chemical processes in furnaces and abrupt changes in temperature. These factors must be reckoned with everywhere. For lining a steam boiler, in whose firebox the temperature does not reach even 1200°, it would seem that a brick capable of withstanding 1500–1600° could serve well; however, a brick rich in quartz is entirely unsuitable for this purpose—it will crack and gradually crumble as a result of sharp changes in temperature. Good clay fireclay brick is of little use for constructing the roofs of Martin furnaces, whereas dinas of medium quality proves very suitable for this purpose. This is explained by the fact that dinas tends to increase in volume when hot, while fireclay clay brick (basic) tends to contract; that is, a flat arch made of basic brick can easily collapse, which has often been observed.

The effort to create material suitable for the various purposes of furnace construction was well illustrated at the exhibition by samples of bricks.

Of the leaners, the following are chiefly used: fireclay (burnt refractory clay), bauxite, and graphite. Chromite iron ore. Among the acidic materials: quartz.

For the special purposes of technology and scientific laboratories there has arisen a need for material of high refractoriness. Of the basic materials, alumina has found fuller use. The production of pure alumina is carried out in electric furnaces with a current of 25 volts and 1500 amperes; Hall, American patent. The use of corundum in ceramic bodies has made it possible to prepare articles that are not afraid of sharp changes in temperature and that possess constancy of volume. The binding material is clay, Portland cement, lime, or gypsum. Bodies containing corundum are successfully used for coating fireclay bricks (basic ones) in order to protect them from the action of chemical agents at high temperatures. For example, for Goldschmidt’s process the firm took out a patent according to which the interior of a crucible for thermite is coated with a mass consisting of soluble glass and powdered corundum. Coatings of this kind greatly promote the durability of crucibles and furnaces. Diamantine also belongs to this same category of coatings (Die Chemische Industrie, 1905, p. 643).

Fused magnesia has made it possible also to prepare products that are not afraid of a sharp change of temperature. According to the analysis of Arndt (Chemiker–Ztg. 1906, No. 20), the composition of magnesite products is as follows,—apart from magnesia:

SiO₂	0.07%
Fe₂O₃	0.08%
Al₂O₃	0.22—
CaO	none.

Another refractory material, which is acquiring ever greater importance, as is corundum, is carborundum. Carborundum is used for coating and finishing fireclay refractory articles, in order to impart to them the highest resistance to destructive chemical agents in the furnace in connection with their high temperature.

The practice of factory laboratories is closely connected with production, and therefore it will not be superfluous to review what has been done in this field.

Of very great importance is the exact determination of alumina in ceramic bodies and especially in glazes. The precipitation of alumina by ammonia according to F. H. Hinrichsen (Tonindustrie–Ztg. 1907, S. 1145, 1513) in the presence of fluorine compounds does not proceed quantitatively, since, in addition to
Al₂O₃ + 3H₂O + 6NH₄Fl ↔ Al₂Fl₆ + 6NH₄OH,
a double salt, AlFl₆(NH₄)₃, is formed. This also applies to the analysis of silicates by decomposing them with hydrofluoric acid.

E. Ebler (Zeitschr. anal. Chem. 48, 175—179) gives a method for determining barium, based on the insolubility of barium chloride in concentrated hydrochloric acid, in which the chlorides of strontium and calcium readily dissolve. The alkaline earths (carbonates) are dissolved in as small an amount as possible of dilute hydrochloric acid (10 n.). The precipitated barium chloride is collected on a hardened filter. The filtrate is evaporated to dryness; the residue is dissolved in as small an amount of water as possible, and strontium sulfate is precipitated with 0.15% sulfuric acid. After standing for an hour, the strontium sulfate is filtered off. From the filtrate, calcium is precipitated with ammonium oxalate from an ammoniacal solution.

W. Strecker (Chem. Ztg. 31, S. 1217) found under what conditions iron is precipitated quantitatively by ammonia or caustic soda in the presence of tartaric acid. Richard B. Moore and J. Miller (Journ. Americ. chem. soc. 30, 593—594) recommend using pyridine for the precipitation of iron. Edmond Knecht and Eva

Hilbert (Ber. Deutsch. chem. Ges. 40, 3819–3827) gave a method for determining trivalent iron by titration with a solution of titanium trichloride. The end of the reaction is recognized by the disappearance of the red coloration of the solution being titrated from potassium thiocyanate as an indicator. H. Bollenbach (Chem. Ztg. 32, 146–148) gave another method. The reduction of trivalent iron is carried out with sodium hydrosulfite; the indicator is potassium thiocyanate.

K. Schröder (Zeitschr. f. öffentl. Chem. 14, 477–492) points out the influence of copper on the results of analysis by the Zimmermann–Reinhardt volumetric method.

An elegant method for determining potassium in silicates is given by W. Autenrieth (Zentralbl. f. Mineral. u. Geologie 1908, p. 513). For the separation of potassium from other metals, cobalt-sodium nitrite is used. The potassium is weighed in the form of potassium chloride. The method was reported in Sprechsaal.

For determining calcium in magnesites, F. Hundeshagen (Zeitschr. f. öffentl. Ch. 15, 85) recommends precipitating the calcium in the form of sulfate from a strongly alcoholic solution. Vl. Yuferev (Tonind. Ztg. 1908, p. 280, Cement 1909, No. 1) studies the properties of sugar water as a solvent for lime in the presence of silicates.

L. Chugaev (Compt. rend. 145, 679) gives a method for separating nickel from cobalt, zinc, manganese, iron, and chromium with the aid of dimethylglyoxime. O. Brunck (Zeitschr. f. angew. Ch. 20, 834, 1844–1850) confirms the possibility of quantitative separation of nickel with the aid of dimethylglyoxime.

Ch. Fribourg describes the course of analysis of lead white and red lead. Attention is drawn to the contamination of lead white and red lead with manganese peroxide, iron oxide, barium sulfate, and silica. J. F. Sucher (Chem. Ztg. 32, pp. 62–63) describes the testing of red lead.

M. Dittrich and S. Freund (Zeitschr. f. anorg. Ch. 56, 337–343) studied the precipitation of titanium and zirconium in the presence of iron. H. D. Newton (Zeitsch. f. anorg. Ch. 57, 278–280) and F. Willy Hinrichsen give methods for the volumetric determination of titanium. Hinrichsen carries out the analysis as follows. Tetravalent titanium is converted, with the aid of zinc-magnesium, into the trivalent state and is titrated with ferric chloride.

J. Tambon (Bull. soc. chim de France [4] 1, 813) gives a method for separating zinc oxide from impurities by dissolving it in the so-called triple ammoniacal liquid, a mixture of ammonia, ammonium chloride, and ammonium carbonate.

G. Bertrand and M. Javillier (Compt. rend. 145, 924–926) precipitate zinc from an ammoniacal solution with milk of lime; the ammonia

is driven off, while the zinc dissolves again and is precipitated by hydrogen sulfide.

The development of analytical methods in chemistry will have especially important significance in the manufacture of enamels, where often insignificant fractions of certain elements have a decisive importance for the suitability of enamels.

As for the investigation of ceramic kilns, two works were undertaken in this direction. Vl. Juferev (Tonind. Ztg. 31, 1907, p. 1476) examines the influence of the kiln charge (the degree of filling of the chambers) on fuel consumption, and A. V. Bleininger (Tonind. Ztg. 32, 1908, 616) gave a heat balance for a brick kiln.

December 1910.

Plan of the exhibition

To the report of the business traveler V. F. Kuffer.

Plan of the exhibition
grounds.

![Plan fragment with exhibition stands, street names, and restaurant areas.]

Visible inscriptions on the plan:

• Restaurant
• Jahn-Str.
• March-Strasse
• Matthesus-Str.
• Lewinski-Str.
• Kühlneis-Str.
• Mendel-Str.
• Straßburger
• Main restaurant

Visible stand numbers include:

415, 416, 417, 419, 420, 421, 422, 425, 429, 433–434, 435, 436, 438, 439, 440, 441, 442, 443, 444, 451, 452, 457, 498, 499, 500, 501, 503, 509, 510, 511.

![Technical drawing of a machine mechanism.]

Fig. 5.

Fig. 2.

Fig. 3.

Labels visible in the section detail: A, B, C, D, E, F, H, O, S.

Fig. 5.

Arrangement of the cylindrical wall of the apparatus.

Labels visible in the diagram:

• Diaphragm.
• Perforated.
• Cone generatrix.
• Cylindrical wall of the apparatus.
• Perforated.

Fig. 35.

Plan of the lower floor.

Labels visible in the plan:

• Department for inspection of brown goods.
• Air duct.
• Window to the courtyard.
• Fig. 35.

Fig. 36.

Plan of the upper floor.

Labels visible in the plan:

• Department for inspection of white goods.
• Fig. 36.

Fig. 37.

Section along A–B.

Labels visible in the section:

• Fig. 37.
• A
• B
• G
• 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

Fig. 7.

Details of the control unit with friction sieves.

Fig. 8.

Arrangement of the sorbent of the apparatus.

Labels visible in the diagram:

• Fig. 8.
• Arrangement of the sorbent of the apparatus.

Fig. 11.

Loading screw.

Labels visible in the diagram:

• Loading screw.
• Fig. 11.

Valve.

Fig. 9.

Vertical plate of the [[unclear: device name]].

Horizontal plate.

Fig. 11.

Fig. 12.

Dimensions shown: 2.6 m; 0.90; 1.60; 1.50; 1.40.

Fig. 13. Longitudinal section.

Cross-section.

Fig. 21.

Fig. 23.

Fig. 25.

1. Mitteilungen d. Materialprüfungsanstalt am Schweiz. Polytechnikum Zürich. Heft 11 (1907). ↩

2. Die Chem. Ind. 30, 1907, pp. 78–85. ↩