152 PROCEEDINGS OF THE AMERICAN ACADEMY 



The curd remaining on the filter is removed from the funnel and 

 placed on a watch glass, dried at 105", and weiglied ; it is then treated 

 with benzine in a funnel which has a stopper in it, and is covered with 

 a tight fitting watch glass ; one or two soakings serve to completely 

 remove the fat. It is again dried and weighed. I have not as a rule 

 found this determination of fat very satisfactory ; it is apt to be too 

 liigh, from the great difficulty of drying the greasy curd and filter; 

 after the fat is removed, the cat^eine is very easily dried. The object 

 in this set of analysis being rather to endeavor to find a series of con- 

 stants which might be relied upon for determining the question of 

 adulteration, no further examination of the caseine was made for ash, 

 but the portion remaining on the filter after the removal of the fat was 

 regarded as pure caseine. In all my determinations, I found that 

 there was invariably a discrepancy between the sums of the caseine, 

 fat, sugar, and ash, and the total solids as determined by evapora- 

 tion. This varied from .43 per cent to 1.92 per cent, with an average 

 of .87 ; this is owing most likely to the albumen of the milk in part, 

 which is not precipitated by the acetic acid at 4o°-o0° C, and in part 

 to the solubility of the caseine in acetic acid. As will be seen from 

 the table annexed, the sugar seems to be the most constant constitu- 

 ent. The fat varies very much ; the specific gravity is not to be relied 

 upon. Wanklin's test of solids not fat is departed from in a number 

 of instances, and the total solids fall as low as 11.64, while according 

 to the English authorities they should never in pure milk be below 

 9 per cent for the solids not fat, and 12 per cent for total solids. 



In summing up, I must call attention to the remarkably high aver- 

 age of this inilk, 14.49 per cent of total solids, but .06 short of Pro- 

 fessor Babcock's result, with three times the number of specimens 

 which he examined. For purposes of comparison, I annex two other 

 tables, one giving all the average results I have been able to collect 

 up to the present time, and the other giving the extreme variations 

 that have been observed. 



SPECIMENS EXAMINED. 



A. Milk supplied me by a resident of Cambridge, said to be pure Al- 



derney. 



B. Milk from an Alderney cow kept by Dr. James R. Nichols for the 



supply of his family. 



C. Grade cow, Ilerford and Ayrshire. Four years old, had been 



milking twelve weeks and gave sixteen quarts per day. Feed, 



