488 Report OF THE CHEMIST OF THE 
= 
carbon dioxide at ordinary temperatures—The method employed 
in making the comparison was, briefly, asfollows: About ten gramis 
of milk were used in each case. This amount of milk was diluted 
with water at 40°- 42° C. to 100 cc. and then 1.5 cc. of a solution 
containing ten per cent. of acetic acid were added and the solution 
was carefully stirred with a glass rod. The resulting precipitate 
was washed two or three times by decantation and on the filter ; 
finally, the filter-paper and contents were digested according to 
the Kjeldahl method for determining nitrogen. In the other 
case, the milk was diluted to 100 cc. with water of the tempera- 
ture of the room, then 1.5 cc. of the same dilute acetic acid as 
that employed above were added, after which a stream of carbon 
dioxide was passed through the solution, until the liquid above 
the precipitate was clear or very nearly so. The subsequent fil- 
tration, washing and determination of nitrogen were made as 
above. 
The following results were obtained by the two methods with 
two different samples of milk, triplicate determinations being 
made in each case: | 











Method B, 
precipitation 
Method A, with aid of 
precipitation carbon diox- 
at40°C.,sam- ide, sample 
ple Ne. 1. No. 1. 
(c2), Aer. OONty NILTOL ON. 5). sie t/0's oe he oe Ree ois 0.475 0.486 
A eiemcent mitroveny (2% bia ack oniies eines 0.474 0.480 
(ey etrerroonte TH tTOS eps yy swe cuckts aes sede bra ceels 0.469 0.461 
EA DEAUG.iycccl tects oie aes SRI Ee scree ae 0.473 0.476 
Sample No. 2. Sample No 2. 
Cijer ercent, Mifroven 20%), Gees shee pe 0.458 0.454 
(A)eerrcen tb. DitroOgennd. io Wma xn se > 0.458 0.444 
(Cheb ercents nitropenin Orts. Wi Mente tae 0.449 0.455 
BAU LAU Oil ous eave tiatuues rial Chidiad, Rte Re 0.455 0.451 
Statement of results — The- above results indicate, first, that 
essentially the same results are obtained whether we precipitate 
the casein in cows’ milk at a temperature of 40° C. without car- 
bon dioxide, or at ordinary temperatures with the aid of carbon 
dioxide, other conditions being uniform. In sample No. 1, the — 
results differed by 0.003 per cent. of nitrogen; in sample No. 2 
