HENRIK LUNDEGÅRDH. Prof. Die quantitative Spektralanalyse der Elemente. Zweiter Teil. Methodische Verbesserungen und praktische Anleitung für die Ausführung von Analysen in den Gebieten der Biologie, Medizin, Agrikulturchemie und des Bergbaus. Mit 39 Abb. im Text und 3 Taf., Jena, Verlag von Gustav Fischer, 1934. S. 124.

HENRIK LUNDEGÅRDH, Prof. Quantitative Spectral Analysis of Elements, Part II. Improved methods and practical instructions for performing analyses in the fields of biology, medicine, agricultural chemistry, and mining.

The book under review is, in essence, the second edition of the monograph by the same author—an outstanding specialist in spectral analysis—which appeared in 1929. Lunde­gårdh has already been working for several decades in this field, applying in it a number of original and distinctive methods. Naturally, he devotes the chief attention to describing them, which lends considerable interest to the book under review.

Lundegårdh is one of the few workers in spectral analysis who systematically uses an oxygen–acetylene flame as the light source. The sprayer he has designed and described in detail has now been so perfected that it permits analyses for 30 elements to be carried out with an absolute accuracy exceeding that of ordinary chemical and colorimetric methods. The main details of its construction are the extremely small diameter of the opening and the delivery of the solution being studied under a pressure of two atmospheres. This latter circumstance, of course, cannot be counted among the merits of the method, since it complicates an already complex system of feeding the light source (in comparison with the spark and the voltaic arc usually used). The solution under study is consumed very sparingly, since its excess is collected in the receiver of the sprayer and can be used again. The blackening of spectral lines is estimated not visually, as usual, but with the aid of Moll’s microphotometer, to whose detailed description several pages are devoted. The blackening of a given line is determined from the deflection of the galvanometer pointer; at the same time a correction is introduced for the blackening of the surrounding background of the line, which is rather strong in the flame. If the concentration of the element to be determined is too high, the author recommends, instead of excessively reducing the exposure (in order to avoid accidental fluctuations in the flame intensity), reducing the intensity of the lines by inserting a rotating sector or a gray wedge, or simply diluting the solution. A necessary condition for analyzing solutions is the absence of small suspended particles that clog the openings in the sprayer and reduce the accuracy of the results. Colloids do not interfere with the operation of the sprayer.

In general, it should be noted that the author attaches enormous, perhaps even exaggerated, importance to the homogeneity of the substance introduced into the light source. For accurate analyses he recommends using only solutions—even when analyzing alloys and metals. Especially for work with solutions he has constructed “plunging” or “emerging” spark and arc (Tauchfunke and Tauchbogen). Their principle of operation recalls the interrupting arc (Abreissbogen) described by Gerlach**; however, whereas in Gerlach’s arc, after ignition, it automatically breaks and ignites again, the action of the emerging spark (arc) is considerably more complex. After ignition it automatically breaks, then plunges into a vessel filled with the solution being analyzed (the circuit closed through the electrodes is thereby broken); after this the electrodes are automatically withdrawn from the solution, the spark (arc) ignites, breaks again, the electrodes are immersed in the solution, and so on. In the accuracy of analytical results the spark of such a device, according to the author, is only slightly inferior to the flame; as for the “emerging” arc, it is very sensitive—

* H. Lundegårdh, Die quantitative Spektralanalyse der Elemente.

* W. Gerlach u. W. e. Gerlach, Die chemische Emissionsspektralaufnahme*, II Teil, Leipzig 1933.

reliable, but so far it permits only semiquantitative determinations. The author accompanies the detailed description of the device for the “diving” spark (arc) with detailed tables of the last lines obtained with the aid of the first of these devices. A substantial feature of these tables is the detailed study, carried out by the author, of the last lines of the rare earths—an ordinary gap in manuals on spectral analysis.

Of extraordinary interest is the section of the monograph devoted to the direct photometry of spectral lines with the aid of a photocell. In this procedure the quartz spectrograph is replaced by a quartz monochromator; at its exit slit a diaphragm with a quartz-window photocell is installed. Work is possible with a slit width of \(0.08\)—\(0.1\) mm. Particular attention must be paid to the absence of disturbances, for which good shielding of all conductors and reliable contacts are necessary. As a light source one may use a flame or an arc, but not a spark. The photocell gives readings corresponding to instantaneous intensity values; therefore it is necessary to make a series of readings (for example, for 100 sec. every 10 sec.) and then average them.

In conclusion we shall mention two interesting technical procedures described by the author. The first concerns the question, a painful one for spectral analysis, of the determination of anions. As is known, by the usual methods of spectral analysis metals and only certain metalloids can be determined. The principle of the author’s method is as follows: the concentration is determined of the cation that forms an insoluble compound with the anion. For the determination of halides \(AgNO_3\) is used; for the determination of \(SO_4\), \(SrCl_2\) is used. This method was applied for the determination of the absorption of anions by various nutrient media. The second procedure concerns the continuous feeding of the analyzed powdery substance (ore) into the flame and recalls the method used in the classical investigations of Eder and Valenta*: a continuously rotating horizontal disk of asbestos touches the analyzed powder with one edge; the other edge passes through the flame, effecting its continuous and uniform feeding.

Summing up, one may say that Lundegårdh’s monograph undoubtedly does not have the fundamental significance that Gerlach’s monograph has**. However, for persons wishing to use a flame as a light source, it will be extraordinarily interesting, chiefly because of its very detailed description of the installation and the large number of valuable practical tips and instructions. The method of direct photometry with the aid of a photocell also seems to us to have a great future; in certain cases it undoubtedly has a number of advantages in comparison with a photographic plate. As for the “diving” arc and spark described by the author, the convenience they create will compensate for the complexity of their design to such an extent that these devices will become common instruments in every spectral-analytical laboratory alongside Gerlach’s intermittent arc.

Ya. Larionov, Leningrad

* J. M. Eder u. E. Valenta, Atlas typischer Spektra, Wien 1928.
* W. Gerlach, Die chemische Emissionsspektralanalyse*, Leipzig 1933; W. Gerlach u. We. Gerlach, l. c.