New YorK AGRICULTURAL EXPERIMENT STATION. 155 
ANALYTICAL DETERMINATIONS. 
The following determinations were made, either wholly or in 
part, in each of the experiments described in this bulletin: 
(1) Total nitrogen in cheese, (2) water-soluble nitrogen, (3) 
nitrogen soluble in 5 per ct. solution of sodium chloride, (4) 
the amount of N-io alkali neutralized hy the water-extract from 
Ioo grams of cheese, (5) the percentage of lactose in cheese, 
(6) the percentage of lime (CaO) and phosphoric acid (P,O,) 
compounds in cheese, (7) the percentage of water-soluble lime 
(CaO) and phosphoric acid (P,O,;) compounds found in cheese, 
(8) the percentage of inorganic phosphorus in cheese in the form 
of phosphoric acid (P,O,) compounds, (9) the percentage of 
calcium (CaO) compounds in the salt-extract of cheese, (10) the 
percentage of lactic acid in the form of calcium lactate in cheese, 
and (11) the percentage of total and water-soluble ash in cheese. 
The amount of nitrogen in the different forms was determined 
in the manner described in Bulletin 215 of this Station, except 
that, in case of water-soluble and salt-soluble nitrogen, the ex- 
traction was continued until I,000 cc. of extract had been ob- 
tained. In all cases, the cheese was first extracted with water 
before treatment with salt solution. In those cases in which 
calcium was determined in the salt-extract, we used for extrac- 
tion a solution of sodium chloride free from calcium salts. 
The lactic acid in cheese, which is present in the form of 
calcim lactate, was determined by Palm’s method,? which is, in 
brief, as follows: The cheese is acidified with sulphuric acid 
and then extracted with ether. The ether solution 1s evaporated 
to a syrupy consistency and then treated with water. This water 
solution is filtered, treated with lead acetate and then filtered 
from any precipitate that forms. More lead acetate is added to 
the filtrate and then alcoholic ammonia. The lead lactate is thus 
precipitated free from other substances. The precipitate is fil- 
tered and washed with alcohol. The amount of lactic acid is 
determined by loss on careful ignition. In place of lead acetate, 
one may use an excess of freshly precipitated lead hydroxide 
to precipitate the lactic acid, especially when the amount is 
small. From the precipitate thus obtained, one may separate 
pure lactic acid by treatment with hydrogen sulphide and subse- 
quent extraction with ether. This method is not altogether 
satisfactory, but appears to be the most efficient one available. 
© *Ztschr. Analyt. Chem., 26, 33. 1887. 


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