New York AGRICULTURAL EXPERIMENT STATION. 493 
applicable to milk that had undergone more or less change; 
or that the formation of lactic acid might make necessary the 
use of less acetic acid than is used in precipitating the casein of 
fresh milk. It was generally found that, after milk had stood 
at a temperature of 17° to 22° C. for twenty-four hours or 
more, the use of 1.5 cc. of a ten per cent. solution. of acetic 
acid gave low results, the filtrate being decidedly turbid. In 
some cases the casein was almost entirely rendered soluble and 
passed into the filtrate. It was found that the only method of 
handling milk under such circumstances was to add the acetic 
acid to the milk, diluted with water at 40°-42° C., in small por- 
tions of a few drops at a time, stirring after each addition and 
continuing the additions until the liquid above the precipitate 
became clear or nearly so. But even with this treatment, 
there was found to be more or less loss. The terms “fresh ” 
and “old” milk are, of necessity, rather vague. Much depends 
upon the conditions under which milk is kept. The extent of 
change rather than the actual age of the milk should form the 
basis of distinction. Coagulated milk gave low results. 

Per cent. of 


; ; Amount 
By ae in precipitate, | of loss. 
FPOBD Ne sites gtd siete e 0.429 |) nie ante 
Sample No. 1.......... | Seven days......... 0.378 | 0.051 
(RE OSTA Wate nrocee ers 's : O.447 oa 
CONG ROAAY: och haley aia shal 0.427 0.020 
Sample No. 2.......... Three days........- 0.428 0.019 
| Seven days......... 0.428 0.019 
Breshys OPQ wea. ¢ 0.428 Pcie 
Sample No. 8.......... Oneidayhy «cia ch 0.410] 0.018 
; HOYER es aueAc are 3 oe 0.438, neous 
ample No. 4....:.... ' OQnerdaygs. vie. 0.415 | 0.023 
MTL a i Nei on ian anal A OG 245 | eererrse 
Sample No. 5.......... One dayne caries: 0.617} 0.007 
PEOSIR Mee ee ai oc oyna: ety OV. 302 aioe 
ample No. 6.......... Onerdayeet cee 0.897 0.000 
HGPOS Lae g y eer ear eltam 0.466. coe ee | 
Bample No. 7.......... Onecday sd, adeiaee 0.445 0.021 

The author has in progress an investigation relating to the 
detailed changes that take place in the nitrogen compounds of 
milk under various conditions. 
