GUIDES IN DETERMINING PURITY. 195 



Amaranth: 0.53; 1.37; 1.65; 1.90; 3.69; 3.71. (Average, 2.14.^ 

 Light Green SF Yellowish: 0.22; 0.47; 0.81; 1.02. (Average, 0.63.) 

 Erythrosin: 0.72. 

 hi'ligo Disulpho Acid: 1.23; 1.36; 1.84. (Average, 1. 48.) 



Work subsequent to these analyses showed that the insoluble 

 matter, particularly the nonvolatile insoluble matter, was greater 

 in certain batches than in others, and that these amounts were in 

 excess of the maximum amounts reported therefor. Examination 

 showed that these increased amounts of insoluble matter were 

 probably due to variations in the water delivered to the factories 

 by their respective municipal water supplies, since it was noted that 

 in two or more cases the batches containing an exceptionally large 

 amount of nonvolatile insoluble matter were manufactured at a 

 time when the city water supply was abnormally hard; this item, 

 therefore, has been made in some instances a little more elastic than 

 the preceding analyses would seem to justify. 



Arsenic. Examination of the preceding tabulations shows that 

 14 out of 30 specimens tested passed the Gutzeit test for arsenic, and 

 16 failed to pass. 



Heavy metals. Inspection of the preceding tables shows that 13 

 out of 30 specimens passed this test, and that 17 failed to pass. 



Combined arsenic and heavy metals test. Inspection of the preceding 

 tables shows that 11 out of 30 passed both tests jointly; that 3 

 passed the arsenic test and failed to pass the heavy metals test; and 

 that 2 passed the heavy metals test and failed to pass the arsenic 

 test. 



Moisture. The amount of moisture, as inspection of the preceding 

 analyses shows, is variable, and is a factor not under easy control. 

 As long as the coloring matters submitted for foundation certification 

 were in powder form and the analyses disclosed the actual percentage 

 of coloring matter it was considered that any control of this item 

 would involve an amount of labor and provide opportunities for 

 friction wholly out of proportion to any benefit that at present could 

 be realized therefrom. Therefore such control was not instituted, 

 although it by no means follows that the time may not come when 

 control of this item will be necessary. 



Sulphur and sulphated ash. These two determinations in the 

 case of all the permitted colors, except Erythrosin, give a rough 

 measure of the extent of the sulphonation and of the saturation of 

 the sulphonic acids with sodium. It is not the function of these 

 two items to exclude the isomeric modifications, nor was any test 

 applied to such of these 30 specimens as were examined in this respect 

 to determine the presence or absence of such products. The attempts 

 made in this direction are of a later date than the analyses already 

 reported, and are indicated on page 210 of this report. 



