110 



FOODS AND FOOD ADULTERANTS. 



or solution of the albumens does not clearly appear. Illustrations of 

 this decrease are seen in analyses 2, 12, 13, and 17. 



It seems to make little difference whether the precipatition is made 

 ho.t or cold. The question of temperature is set forth in greater detail 

 in the next table. From all the experiments made it clearly appeared 

 that the best optical results are obtained by the use of a minimum quan- 

 tity of basic lead acetate, or of either the acid mercuric nitrate or iodide. 

 For 50cc. to 60cc. of milk, Ice. of the lead acetate or mercuric nitrate solu- 

 tion of the strength noted, and 25cc. of the mercuric iodide solution are 

 the proper quantities. It makes no difference, however, if a large excess 

 of the two latter reagents is employed. Of the three the last is to be 

 preferred. 



In Table No. 10 will be found the results of the comparative determina- 

 tions of milk sugar by extraction with alcohol, by precipitation with Ice. 

 basic lead acetate, and the same with Ice. acid mercuric nitrate, hot and 

 cold, to each 60cc. of milk. 



In many of the analyses the large differences in results by the three 

 methods show a fault of manipulation, but all the results have been 

 given without selection. 



TABLE No. 10. Percentage of milk sugar. 



In the following table will be found the percentage of milk sugar ob- \ 

 tained by using varying quantities of the mercuric iodide reagent, and i 

 a comparison of the results obtained with those given by the use of acid 

 mercuric nitrate and basic plumbic acetate: 



