148 REPORT OF THE CHEMIST OF THE 
The whole milk, unpasteurized, coagulated in four days; the 
unpasteurized, carbonated milk, in 35 days; while the pasteur- 
ized, carbonated milk showed only about 0.3 per ct. of acid 
at the end of 35 days. We used the last bottle of the series for 
examination’ at this time and could not, therefore, tell how 
much longer the milk would have kept. 
SEVENTH EXPERIMENT: EFFECT OF TREATING PASTEURIZED MILK 
WITH CARBON DIOXIDE UNDER HIGHER PRESSURE. 
Fresh, whole milk, pasteurized at 185° F., was bottled and 
charged with carbon dioxide gas under a pressure of 150 pounds. 
In order to charge milk with the gas at this high pressure, a 
tank (Fig. 6) was used such as is commonly employed for 
charging soda-water fountains. The milk was placed in the 
tank, the carbon dioxide run in at the desired pressure and com- 
pletely mixed with the milk by rocking the tank. The milk thus 
charged was run into siphon bottles (Fig. 3). This method was 
found more satisfactory in every way than the one used in pre- 
vious experiments. The bottles of milk were kept at about 40° 
F, The results are given in Table VI. 
TABLE VI.— SHOwING AMOUNT OF ACID IN’ PASTEURIZED, FRESH, WHOLE 
MitkK CARBONATED UNDER PRESSURE OF: 150 POUNDS. 
Age of milk. Per ct. of acidity. Age of milk. Per ct. of acidity. 
NEU ee) guage Noes Serr gA eT nee Peay ROIS 0.19 S weeks. a7 3. %c. 3h eee 0.25 
Dewees bamaars> < Fe RATES SAD 0725 9 weeks. G22... SS eee 0.20 
Dano Sols ee Quen ey eres DENS ae al ke MRO a Pia 2 Str Dez? 10 weeks 6.6 hs oc te ) 2a 
SAME Lee Veoh ko eck ae abd ee cere 0.27 1d weeks. 4f45 2 3c 2. oe eee )} 22 
AWE GICE Morne hetaiovct ake PE, ee ee QS; 13, wéeks,ece s,s cus Be Ov 27 
BIW CEKS LID EARL TESS 2 Soutien eerie 0.29 AO-weeks:; & ..0¢-s45 ts oe aieha el ee eee 0.29 
Or Weeksn oie oleee foe tat ee eee 0.23 40 weeks... .te. ou. oe eee 0.31 
T WRCELES Siti et Re aes 9 ire ee eee ae 0.25 




The results show that fresh, whole milk, pasteurized and 
charged with carbon dioxide gas under a pressure of 150 pounds, 
formed practically no increase of acid in the course of about 
nine months. The milk was kept at a temperature varying from 
40° to 60° F. } 
EIGHTH EXPERIMENT: EFFECT OF TREATING FRESH MILK WITH 
CARBON DIOXIDE UNDER PRESSURE OF 175 POUNDS. 
The milk used was obtained under the best hygienic condi- 
tidns, cooled to about 35° F. as soon as drawn and charged with 
carbon dioxide seven or eight hours later under a pressure of 
175 pounds. The results are given below. | 
