576 



SCIENCE 



[N. S. Vol. L. No. 1303 



thermic decompositions. The laboratory methods 

 used are designed to deal with decompositions in 

 both solid and dust air phases. Preliminary re- 

 sults are promising finding application in plant 

 practise, insuring more uniform quality in the 

 dyes produced. 



Some problems in the identification of dyes: E. 

 F. Hitch and I. E. Knapp. It is pointed out that 

 before the American dyestuff manufacturers can 

 develop new colors, they must be able to duplicate 

 the staple foreign dyes, especially the more recent 

 ones, and those which are unclassified. In order 

 to do this it will be necessary to identify these 

 dyes, and in many instances to determine their 

 chemical constitution. The first class of prob- 

 lems that are likely to be met includes (1) the 

 identification of two or more dyestuffs, the com- 

 position of one of which is known; (2) the de- 

 termination of the chemical constitution of an un- 

 known dyestuff; and (3) the separation and 

 identification of the component of a mixture of 

 dyestuffs. The problems in class two deal with the 

 identification of dyestuffs on the fiber. The meth- 

 ods which have been proposed for the solution of 

 these problems are reviewed. In conclusion, a 

 plea is made for closer cooperation between the 

 universities and the dyestuff industry. Several 

 ways are shown in which such cooperation might 

 be effected. 



Indicators and their industrial application: H. 

 A. LuBS. The most recent and useful develop- 

 ments in the field of indicators are largely due to 

 need for a series of brilliant and sensitive com- 

 pounds for the colorimetric determination of H+ ion 

 concentration of biological fluids. This necessity 

 has given rise to the study of the ranges, and of 

 the salt, protein and other errors of a large num- 

 ber of compounds, as well as to the synthesis of 

 new indicators. The sulfophthalein series of indi- 

 cators are brilliant compounds and cover a wide 

 range of H+ ion concentration. These compounds 

 are superior in a number of respects to indicators 

 in general use at the present time and their appli- 

 cation in a number of industrial operations would 

 be highly advantageous. The lack of reliability 

 in the case of test papers of litmus and pheuolph- 

 thalein is pointed out and the use of sulf ophthaleins 

 is suggested. Examples of certain procedures in 

 the preparation of dyes and intermediates in 

 which indicators can be of assistance are given. 



Vat dyes : M. L. Ckosslet. 



Gentian, violet and its selective bactericidal ac- 

 tion: M. L. Ckossley. 



The importance of intensive and original research 

 in the development of the dye industry in America : 

 M. L. Ceossley. 



Logwood in its relation to the silk indvMry: 

 Emil Lessee and David Wallace. 



Some engineering aspects in the manufacture of 

 dyes: Clarence K. Simon. 



Observations on the estimation of the strength 

 of dyes : W. H. Watkins. 



Application of physical chemistry research on 

 dyes: E. K. Strachan. 



Crystallographic identification of five isocy amines: 

 Edgae T. Wheeet. Five isomeric or closely re- 

 lated isocyanine dyes have been prepared in the 

 Color Investigation Laboratory of the Bureau of 

 Chemistry by Dr. E. Q. Adams, and crystallized 

 from alcohol. The crystals prove to show brilliant 

 color phenomena, and especially the rare effect 

 known as refiection-pleochroism, the reflection of 

 light of different colors in different crystallo- 

 graphic directions. Models of these crystals have 

 been prepared (and were exhibited at the meet- 

 ing) . It is ordinarily not practicable for any 

 one not specifically trained in crystallography to 

 carry out measurements of interfacial angles of 

 random crystals, because it is a matter of great 

 difficulty to orient given crystals correctly. The 

 fact that the crystals of these dyes have definite 

 colors associated with definite crystallographic di- 

 rections makes such orientation comparatively easy, 

 and which dye is represented in a given sample 

 can be rapidly and certainly ascertained by a few 

 simple observations of angles, far more readily 

 than by any known chemical method. 



The dye situation in the United States and Eng- 

 land: T. FEtfSHER. Charles L. Paesons, 



Secretary 

 (To be continued) 



SCIENCE 



A Weekly Journal devoted to the Advancement of 

 Science, publishing the official notices and pro- 

 ceedings of the American Association for 

 the Advancement of Science 



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