184 COAL-TAR COLORS USED IN FOOD PRODUCTS. 



with hydrochloric acid, bring the two solutions together and slightly acidify with 

 hydrochloric acid; dilute to 100 cc; place 10 cc in a test tube of 40 cc capacity and 

 warm to 50 C. in a water bath; add 10 cc of a freshly prepared saturated solution of 

 hydrogen sulphid in water, stopper the test tube well and allow the whole to stand 

 in water having a temperature of 35 C. for a half hour. Dilute a 3.3 cc portion to 10 cc, 

 treat as before with 10 cc of hydrogen sulphid in water for one-half hour at 35 C., and 

 add to each ammonium hydrate. 



TOTAL INSOLUBLES. 



Dissolve 1 gram of the substance in 1 liter of water, filter through counterpoised 

 quantitative filters, and wash with hot water until all traces of color are removed 

 from the filter paper, then dry at 100 C. to constant weight and weigh; report the 

 weight as total insolubles. Ignite the total insolubles in a platinum crucible and report 

 the residue remaining as nonvolatile insolubles. 



ETHER EXTRACTIVE. 



Two methods were employed, the one consisting in direct extraction of the sub- 

 stance in a Soxhlet apparatus by means of redistilled ether dried over sodium. 

 Schleicher & Schiill extraction cartridges were used after they had been thoroughly 

 extracted by ether and shown by examination that they yielded no extractive to 

 ether whatever. This is a necessary precaution, because the amount of ether extrac- 

 tive matter in these cartridges varies. The amount of ether extractive was determined 

 by driving off the ether over a 32-candlepower incandescent lamp, finally drying and 

 cooling in a desiccator. 



This method, however, is not satisfactory, since the results it gives are undoubtedly 

 low and it seems that the higher the material was dried the more erratic were the 

 results. Therefore the following method was used: 



Disolve 1 gram of the sample in 100 cc of water; add 0.5 gram of sodium acetate; 

 extract three times with 50 cc of ether in aseparatory funnel; mix the ether so recov- 

 ered with 10 cc of water; separate the ether and dry with fused calcium chlorid; let 

 stand from 12 to 24 hours; pour off from the calcium chlorid; distil off the ether as 

 in the preceding method; acidify the color solution containing sodium acetate with 

 1 cc concentrated hydrochloric acid; extract three times with 50 cc of ether, and 

 proceed as before. 



RESULTS OP CHEMICAL EXAMINATION, 1907. 

 DETAILED CHEMICAL DATA ON EACH PERMITTED COLOR. 



The results of this examination are given in the following tabula- 

 tions under the respective Green Table numbers; the serial num- 

 bers refer to the numbers assigned to the specimens as they were 

 received. The abbreviations "p." and "n. p." opposite "Gutzeit 

 test," and "Heavy metals test" stand for "pass," and "not pass," 

 respectively, according as the specimen did or did not comply with 

 those requirements; the entries opposite "Ratio," indicate the degree 

 of concordance of the sulphated ash as weighed, and the contained 

 SO 3 calculated back to sodium sulphate and is a measure of the accu- 

 racy or dependability of the sulphated ash item and its determination. 



