232 



Dye wool yellow or orange. 



SECTION I. Hydrochloric acid added to strong acidification precipitates the color 

 or decolorizes the solution (the nitro colors). 



Group I. Color extracted by ether from solution acidified with hydrochloric acid. 



Victoria yellow (2). 



Martius yellow (3), water solution plus potassium cyanid gives a brown color on 

 warming. 



Group 11. Color not extracted by ether from solution acidified with hydrochloric 

 acid. 



Naphthol yellow S (4). 



SECTION II. Hydrochloric acid causes a decided change in the color of the water 

 solution (many of the tropceolins). 



Group I. Hydrochloric acid turns dyed wool violet. 



Dyed wool is yellow. 



Brilliant yellow S (Sch.) (89), dyed wool is yellow turned violet by hydrochloric 

 acid. 



Metanil yellow (Sch.) (95), dyed wool is orange yellow turned violet by hydro- 

 chloric acid. 



Group II. Hydrochloric acid turns dyed wool brown. 



Chrysoidin R (18). This color is absorbed by fuller's earth and partially absorbed 

 by aluminum hydroxid. 



Group III. Hydrochloric acid turns dyed wool red. 



Fast yellow (8). 



SECTION III. Color of water solution not decidedly changed by hydrochloric acid. 

 (If a precipitate appears only a part of the color is precipitated.) 



Dyed wool is yellow. 



Naphthol yellow S (4), dyed wool is decolorized b'y hydrochloric acid. 



Tartrazm (94), color of dyed wool not changed by hydrochloric acid. 



Dyed wool is yellow orange to orange. 



Tropoaolin (84). 



Tropceolin 000 (85). 



Orange G (14). 



Dyed wool is red orange. 



Mandarin G (86), dyed wool is turned red violet by hydrochloric acid or sulphuric 

 acid. 



Ponceau 4 G. B., color of dyed wool not changed by hydrochloric acid nor by sul- 

 phuric acid. 



COLORS OP CLASS II. 



Solution decolorized by stannous chlorid, original color returns on addition of 

 hydrogen dioxid. (Bismarck brown, which might be referred to this class, is included 

 under Class I.) 



(1) Dyes wool and cotton bluish red (most readily from an alkaline bath). 

 Safranin (584), much hydrochloric acid turns water solution blue violet. Color 



absorbed by fuller's earth, precipitated by tannin reagent. Sulphuric acid turns 

 dyed wool green, solution green, hydrochloric acid blue. 



(2) Dyes wool blue from alkaline or neutral bath, cotton a paler blue from neutral 

 bath. 



Methylene blue (650), color absorbed by fuller's earth precipitated by tannin; 

 hydrochloric acid turns dyed wool robin 's-egg blue, sulphuric acid green. 



COLORS OP CLASS III. 



Stannous chlorid produces no further effect on the color than hydrochloric acid. 

 Sodium hydroxid produces a precipitate or decolorizes the solution. All the colors 

 given in this class except auramin (425) are decolorized by sodium bisulphite reagent. 



