I'JUU.] PUBLIC DOCUMENT— No. 31. 147 



stance on heating becomes solid or semisolid, due to the forma- 

 tion of a starch paste, hence a slight modification was employed. 

 Method. — To 25 to 50 grams of the sample add 150 cubic 

 centimeters of absolute alcohol^ and 5 cubic centimeters 1 to 1 

 ammonia ; digest with reflux condenser for three-fourths to one 

 hour, filter, acidify with 10 per cent, hydrochloric acid, add 

 about a square inch of woolen cloth and boil from three-fourths 

 to one hour, to effect a good transfer of color. The wool sample 

 is next washed thoroughly in water, boiled for several minutes 

 ill very dilute solution of hydrochloric acid and then again in 

 water, to remove the acid. The color in the wool sample is next 

 dissolved by boiling it in a 1-50 ammonia solution, after which 

 the sample is removed and the bath again made acid, when the 

 second wool samjile is added and the boiling of the second acid 

 bath prolonged from one-half to one hour. " The dyeing of the 

 second wool sample, ranging from a bright canary yellow to a 

 deep reddish yellow, is positive proof of added coal tar color." ^ 

 Of 30 samples of gluten feed collected on the Massachusetts 

 market in 1908, 26, or over 80 per cent., were found to contain 

 added aniline color. This coloring is lawful provided the fact 

 is so stated on the food label, as is now the case with most of 

 the gluten jiroducts placed on sale. 



5. Conclusions. 



1. Water solutions of gluten feed react acid to phenolphtha- 

 Iciu (.1 to 2.11 per cent, calculated as sulphuric acid) and alka- 

 line or neutral to methyl orange, which would indicate the ab- 

 sence of any appreciable amount of free mineral acid (suli^huric 

 and hydrochloric). The direct determination of the sulfates and 

 chlorides shows them to be present only in small amounts. 



2. An analysis of the ash of the water solution shows it to 

 contain considerable potassium, magnesium and phosphoric 

 acid, together with lesser amounts of calcium and sodium. The 

 presence of the several alkalies oifers additional evidence of the 

 absence of free mineral acids. 



3. The presence of such considerable amounts of potassium, 

 magnesium and phosphoric acid in the extract leads one to sur- 



• Jenkins of Connecticut State Station recommends tlic use of alcohol in first acid bath. 

 « Gudcman in Journal American Chemical Society, Vol. XXX., No. 10 (1908), 1623. 



