RESULTS. 19 



two firms sent the same dye under the same or under different names the 

 circumstance is explicitl}' presented. 



Third. Immediately after the commercial name that of the factory is 

 given. The dyes were obtained from three sources. Both the Actiengesell- 

 schaft fiir Anilinfabrikation and Meister, Lucius & Briining presented a large 

 number of d3^es of their manufacture to the Johns Hopkins University. The 

 other d3'es were purchased from the firm of Eimer & Amend, New York. 



The following abbreviations are used throughout. 



[A.] Actiengesellschaft fiir Anilinfabrikation, Berlin (The Berlin Aniline Co.). 



[A. A.C.] The Albany Aniline Color Works, Albany, New York. 



[B.] Badische Anilin-und Sodafabrik, Ludwigshafen am Rhein (The Baden Co.). 



[By.] Farbenfabriken vorm. Fr. Bayer & Co., Elberfeld (The Bayer Co.). 



[C] Leopold Cassella & Co., Frankfurt am Main. 



[D.] Dahl &Co., Barmen. 



[D. H.] L,. Durand, Huguenin & Co., Basle and Huningen. 



[G.] J. R. Geigy, Basle. 



[I. ] Soci6t6 pour 1' Industrie Chimique (formerly Bindschedler & Busch), Basle. 



[K.] Kalle & Co., Biebrich am Rhein. 



[M.] Farbwerke vorm. Meister, L,ucius & Briining, Hochst am Main (Meister, 



Lucius & Briining, Limited). 

 [O.] K. Oehler, Offenbach am Main. 

 [P.] Societe Anonyme des Matieres Colorantes de St. Denis, Paris. 



Fourth. The chemical name of the absorbing medium is given. 



Fifth. Reference is made either to the figure (or figures) and plate 

 which belong to the substance under discussion itself or to a figure which is 

 very much like the spectrograms of the dye considered. 



Sixth. When possible, the number of the dye or the page of the inter- 

 mediate product, as found in the volume of Schultz & Julius, is recorded. 



Seventh. The color and superficial character of the dry coloring matter 

 is suggested. 



Eighth. The color of the solution as observed in a test-tube is followed 

 by the color in the cell. The change of color with thickness is often 

 significant. 



Ninth. Then follows the concentration in grams of dry solvend in a 

 liter of solvent. The term "saturated" is to be understood in its general, 

 practical sense and not in the almost unattainable, theoretical sense. 

 Parenthetical, qualifying words, such as "(heated, filtered)," call attention 

 to the fact that the substance does not dissolve readily in water, or that the 

 solution contained gritt3% foreign material, etc. 



Tenth. Next is given the angle between the quartz plates forming the 

 top and bottom of the various cells used. In the same line the numbers 

 denote in order the minimum and maximum depths of solution through 

 which the light passed before acting upon the outer limits of the negative. 

 The intermediate thicknesses va.Ty linearly, of course. The same angle is not 



