NATURE 



2>^o 



THaRSDAY, AUGUST 4, 1892. 



COAL- TAR COLO URING-MA TTERS. 

 Tabellarische Uebersicht der kiinstlichen organischen 

 Farbstoffe. Von Gustav Schultz und Paul Julius. R. 

 Gaertner's Verlagsbuchhandlung, Hermann Heyfelder. 

 (Berlin, 1891.) 



DR. SCHULTZ is well known to "tar chemists" as 

 the author of " Die Chemie des Steinkohlentheers/ 

 the most exhaustive work on coal-tar products which 

 has hitherto been written, and of which the first edition 

 appeared in 1882, and the second, enlarged to two thick 

 volumes, in 1 887-1 890. His colleague Dr. Julius is 

 the author of a useful little work on the same subject 

 published in 1887. The volume before us is a remarkable 

 production from every point of view, and well worthy of 

 the reputation of the two authors who have collaborated 

 in its production. Although nothing more than a tabu- 

 lated catalogue of coal-tar colouring-matters, as it pro- 

 fesses to be, the work is in reality a complete index to the 

 literature of this rapidly growing branch of industry ; 

 complete, that is to say, to the date of its publication ; but 

 development is taking place even now at such a pace that 

 a single year has sufficed to render a supplement necessary, 

 and many of the most recently added colouring-matters 

 are not included in the lists. The first edition of the 

 "Tabellarische Uebersicht " was published in 1888 and 

 contained 278 colouring-matters; the present edition con- 

 tains 392 colouring-matters— a fact which speaks for 

 itself with respect to the progress of chemical discovery 

 in this direction. The volume is dedicated to the late 

 Prof von Hofmann, whose labours in this field in the early 

 days of the industry will render his name inseparable 

 from that band of pioneers who were the first to penetrate 

 into the new regions opened up by the discovery of mauve 

 by Dr. W. H. Perkin in 1856. 



The volume of tables under consideration has become 

 indispensable to ever>' chemist engaged in the manufacture 

 of, or in any way interested in, the coal-tar colouring- 

 matters. To the general chemist it will be a matter of 

 wonder that from three to four hundred distinct com- 

 pounds, for the most part of known constitution, definite 

 in character, often beautiful in crystalline form and ap- 

 pearance, and, in short, all well-characterised " chemical 

 individuals," should be turned out of factories by 

 hundredweights and tons for consumption in the tinctorial 

 industries. 



The authors group the colouring-matters under sixteen 

 headings :— Nitro-derivatives, Azoxy-compounds, Hydra- 

 zones, Azo-compounds, Nitroso-compounds (quinone- 

 oximes), Oxyketones, Diphenyl-methane derivatives, Tri- 

 phenyl methane derivatives, Indophenols, Oxazines and 

 Thiazines, Azines, Artificial Indigo, Quinoline colouring- 

 matters, Acridine colouring-matters, Thiobenzenyl deriva- 

 tives, and colouring-matters pf unknown constitution. 

 The tables are arranged in eight columns, the first con- 

 taining the commercial name of the colouring-matter, the 

 second its scientific name, the third its empirical formula, 

 the fourth its constitutional formula, the fifth its mode of 

 preparation, the sixth its date of discovery, the seventh 

 the name of the discoverer and literary references, and 

 NO. 1 1 88, VOL. 46] 



the eighth its general properties and mode of application. 

 From this analysis it will be seen that the work is, as we 

 have stated, a complete epitome of the coal-tar colour 

 industry. Its value as a work of reference for tech- 

 nologists will be appreciated by all who may have 

 occasion to consult it ; our own experience has been that 

 the many thousand references to chemical literature, 

 patents, and periodicals, are given with an accuracy that 

 leaves nothing to be desired. One special feature to 

 which attention must be directed is that the compounds 

 tabulated are or have been actual articles of commerce. 

 If the colouring-matter has been superseded, as must 

 inevitably be the case with the progress of discovery, the 

 authors announce the fact by stating nicht mehr tin 

 Handel. Thus the reader is made acquainted with 

 the actual state of the industry, and the student with 

 these tables at hand will be prevented from becoming a 

 prey to the snares of the compilers of examinational 

 text-books, who are only too frequently quite out of touch 

 with the technology of their subject. Writers of this 

 class are apt to set forth lists of compounds which are 

 worthless to the manufacturer, and which are of value 

 only to the examiner in technology by enabling him at 

 once to separate the sheep from the goats among his 

 candidates — to distinguish the students whose knowledge 

 has been derived solely from books from those who are 

 actually engaged in the factory. 



One very forcible truth which is brought home on 

 running the eye down the seventh column of the tables 

 before us is the great preponderance of references to 

 patents, chiefly German. It is evident that the chemist 

 who wishes to keep abreast of modern discovery can no 

 longer afiford to neglect the literature of the Patent Office. 

 Many discoveries of the greatest scientific importance 

 are buried in these specifications, and it is long before 

 they find their way into the text-books. This, so far as 

 we are concerned, is much to be regretted, for, in the 

 first place, the working chemist is already painfully over- 

 burdened with literature, and in the next place the state- 

 ments in specifications require very judicious sifting 

 before they can be admitted as part of scientific know- 

 ledge. The student who is not familiar with the coal-tar 

 colour industry would be hopelessly entangled among the 

 mazes of patent literature were it not for such practical 

 guides as Drs. Schultz and Julius, who have evidently 

 used the greatest judgment in giving their references. In 

 other words, the patents quoted have reference to the 

 production of compounds which are, or were, manufac- 

 tured, and the reader who consults their work may feel 

 assured that the " bogus " or " fishing " patent, which 

 may be so innocently swallowed by the unwary, will not 

 be obtruded on his notice. 



So far as English technologists are concerned, it is to 

 be regretted that such an overwhelming majority of 

 German patents have to be referred to. This, of course, 

 is only to be expected, when we consider the extraordinary 

 activity which the Germans have displayed in the develop- 

 ment of the industry of which the foundations were laid 

 in this country about thirty or forty years ago. But the 

 technological student is thereby placed at a disadvantage 

 because German patents are not very readily obtainable. 

 It is true that all capital discoveries are also patented in 

 this country, but, on the other hand, there are many 



