New York AGRICULTURAL EXPERIMENT STATION. 275 
rence of what is known as “ mottling ” in butter has any relation 
to either of these casein bodies. 
THE RELATION OF CASEIN AND CASEIN LACTATE TO 
CREAM-RIPENING. 
We wished first to ascertain what form of casein compound 
was obtained in the ripening of cream, when the cream showed 
different percentages of acid. Three series of experiments bear- 
ing on this point were made. Some fresh, pasteurized cream was 
treated with a carefully prepared starter in Erlenmeyer flasks, 
stoppered with cotton. These were allowed to stand at room 
temperature, samples being withdrawn for examination from 
time to time. The results of these experiments are given in the 
following table: 
‘TABLE I.—SHOWING. CHEMICAL CHANCES IN CREAM-RIPENING. 


A Nitrogen e 
mount in cream itrogen 
No.of | Atoot | SPRL | Amount | Amount | total | Hagan | eres 
one eee when eueet sugar acid nitrogen of ite af form 
ment. in : and its of casein 
analyzed. eran changed. formed. in cream, eons Taethee: 
pounds, 
Hours Per ct. ! Perv ct. Per ct. Per‘ct. Per’ ct. Per ct 
1 Fresh 3.64 —— 0.15 0.39 0.32 0.00 
1 8 3.58 0.06 0.18 0.39 0.31 — 
1 24 2.92 0.72 0.60 0.38 Uo 0.33 
i 32 2.90 0.74 0.61 0.39 0.30 0.30 
it 48 2.88 0.76 0.62 0.39 0-32 0.32 
1 72 2.90 0.74 0.63 0.38 0.34 0.34 
2 Fresh 3.84 —_-— 0.14 0.41 0.34 0.00 
Pe 24 3.04 0.80 0.64 0.40 0.35 0.35 
3 Fresh 3.81 ——_- 0.14 0.41 0.35 0.00 
3 24 2.93 0.88 0.70 0.40 0.36 0.36 


The following statements are suggested by the data contained 
in Table I: 
(1) Nitrogen compounds in ripened creanm.—When the cream 
was fresh and when it was eight hours old, there was only calci- 
um casein (milk-casein) present, that is, neither of the com- 
pounds (free casein and casein lactate), formed from calcium 
casein by treatment with lactic acid, was present. In 24 hours 
the only casein compound present in the cream was casein lac- 
tate, the compound insoluble in warm dilute salt solution; this 
is the compound commonly observed in milk curdled by ordinary 
souring. In each-of these experiments the cream had eurdle#? 
