METHODS OF ANALYSIS FOR CERTIFIED COLORS. 221 



NITROGEN. 



Determine as given under Ponceau 3R, page 217. 



UGHT GREEN S F YELLOWISH. 

 MOISTURE. 



Determine as given under Ponceau 3R, page 215. 



TOTAL INSOLUBLE MATTER. 



Determine as given under Naphthol Yellow S, page 211. 



NONVOLATILE OR INORGANIC INSOLUBLE MATTER. 



Determine as given under Naphthol Yellow S, page 211. 



SODIUM CHLORID. 



Determine as given under Ponceau 3R, page 215. 



SODIUM SULPHATE. 



Dissolve 5 grams of the color in 100 cc of water, warming by means 

 of a gentle heat. Dissolve 1 1 grams of saf ranin hi a separate portion 

 of 400 cc of water, also by warmhig, taking care hi both instances to 

 prevent loss by evaporation. Mix the two solutions, shake thor- 

 oughly, and filter through a dry filter. Render an aliquot portion 

 of the filtrate alkaline with sodium hydroxid and remove the excess 

 of safranin by shaking with two successive portions of amyl alcohol. 

 Wash the combined amyl alcohol layers with two portions of water 

 and add the washings to the main aqueous solution, which is then 

 acidified with hydrochloric acid and sulphates determined in the usual 

 manner by preciptiation with barium chlorid as barium sulphate. 



HEAVY METALS. 



Determine as given under Naphthol Yellow S, page 212. 



ARSENIC. 

 Determine as given under Naphthol Yellow S, page 212, 



ETHER EXTRACTIVES. 



Determine as given under Naphthol Yellow S, page 214 



SULPHATED ASH. 



Determine as given under Naphthol Yellow S, page 214. 



CALCIUM. 

 Determine as given under Naphthol Yellow S, page 215 



