New York AcricutturRaL ExprrRimMpnt STATION. 175 
NATURE OF THE SAL'I-SOLUBLE PRODUCT. 
(1) A salt of paracasein.— In the case of cheeses made with 
and without lactic acid, in the presence of chloroform, we have 
seen that there were large amounts of the salt-soluble product 
formed when lactic acid was used, and only small amounts when 
no acid was used. We have also seen that, in the case of normal 
cheddar cheeses, the salt-soluble product occurs in large pro- 
portions, increasing in quantity as the milk-sugar disappears, 
or, in other words, as the amount of lactic acid increases. It, 
therefore, appeared to us that, in this salt-soluble product, we 
were dealing with some compound of paracasein and lactic acid, 
probably a paracasein lactate. 
(2) Artificial preparation of paracasein lactate.— It seemed 
desirable to attempt the artificial preparation of the salt-soluble 
product, and to ascertain if it were identical with the substance 
extracted by a dilute solution of sodium chloride from newly- 
made cheese. For the purpose of this comparison, the following 
experiment was undertaken in the artificial preparation of the 
salt-soluble product. 
We coagulated about 6 liters of skim-milk by rennet at 86° F. 
(30° C.). The resulting curd was well washed with water, 
drained and then treated for one-half hour at 122° F. (50° C.,) 
with 3 liters of a 1 per ct. solution of lactic acid. By this treat- 
ment a turbid solution was obtained, which was filtered from 
the large residue remaining undissolved, through cloth first and 
then through absorbent cotton. This filtrate, neutralized with 
dilute potassium hydroxide, gave a copious precipitate, which 
was filtered, washed with water, and redissolved in 1 liter of 
0.5 per ct. solution of lactic acid. This solution was filtered 
and reprecipitated by dilute alkali, and the process of redissolv- 
ing, filtering, and reprecipitating was repeated twice. The re- 
sulting product was finally well washed with water, suspended 
in 95 per ct. alcohol for 2 days and, after removal of alcohol by 
filtration, was extracted 24 hours with ether and dried at 212° 
F. (100° C.). The substance thus prepared was firm and leathery 
in texture, greatly resembling in physical properties the 
product prepared from the salt-extracts of cheese. To all ap- 
