178 REPORT OF THE CHEMIST OF THE 
tion process, upon paracasein under well-controlled conditions, 
and also to compare this action with the one taking place when 
pure dilute lactic acid acts upon paracasein directly without 
any fermentation. For this purpose it was desired to secure 
paracasein or cheese-curd as free as possible from acid. In 
order to prevent all acid fermentation, very fresh, sweet milk 
was treated with ether. In this way it was possible nearly to 
eliminate the formation of paracasein compounds of lactic acid 
at the beginning of the experiment and have as our original 
working material paracasein as nearly as possible free from 
salt-soluble compounds. Two analyses of paracasein, thus pre- 
pared, showed the presence of 3.90 and 4.34 per cent. of the 
total nitrogen in the form of a salt-soluble compound. Several 
bottles were prepared in the following manner: We placed in 
each bottle 25 grams of the carefully prepared cheese-curd or 
paracasein, ground with sand, and added 50 ce. of water; the 
mixture was thoroughly shaken, and then sterilized. To this 
common mixture, various additions were made in the different 
bottles as indicated below: | 
Series A received 0.5 gram of sterile milk-sugar and a pure 
culture of lactic-acid organism. 
Series B, 1 gram of sterile milk-sugar and lactic-acid organism. 
Series C, no milk-sugar and organism. 
Series D, 0.5 gram of pure lactic acid and no organism. 
Series E, 1 gram of pure lactic acid and no organism. 
Series F, 1.5 grams of pure lactic acid and no organism. 
All the bottles were kept at 60° F. (15.5° C.) and analyses 
were made at different periods, as indicated in Table IV. 
