596 
produces pronounced changes. These changes consists mainly of the 
following : 
Decomposition of the lecithin and nuclein. 
Diminution of the organic phosphorous. 
Increase of inorganic phosphorous. 
Precipitation of the calcium and magnesium salts and the greater 
part of the phosphates. 
Expulsion of the greater part of the carbon dioxide. 
Caramelization or burning of a certain portion of the milk sugar 
(lactose) causing the brownish color. 
Partial disarrangement of the normal emulsion and coalescence of 
some of the fat globules. 
Coagulation of the serum albumin, which begins at 75° C. 
The casein is rendered less easy of coagulation by rennet and is 
more slowly and imperfectly acted upon by pepsin and pancreatin. 
Boiling gives the milk a cc cooked ” taste. 
The cream does not rise well, if at all. 
When the milk reaches about 60° C., a scum forms on the surface 
which consists of — 
Fatty matter : 45. 42 
Casein and albuminoid 50. 86 
Ash 3. 72 
Milk heated in closed vessels does not form a pellicle even when 
the temperature reaches 100° or 110° C. Milk heated in the open 
air after cooling forms a pellicle on the surface which renews itself 
if it is removed. It seems that this pellicle is due mainly to the 
drying of the upper layer of the liquid. The cream probably does 
not rise well in heated milk, owing to the increase in the viscosity 
of the liquid in which it is emulsified. 
Heat kills the ferments in milk,® which according to some authors 
play a useful role in digestion and metabolism. We have no direct 
knowledge of the utility of these ferments. For the child to digest 
and assimilate cow’s milk to advantage the complex albuminous sub- 
stances must first be broken down by the processes of digestion into 
simpler products and again synthetized. In other words cow pro- 
teins must be converted into human proteins. In this process fer- 
ments play an essential role. We know that the digestive tube con- 
a Hippius (Deut. med. Woch., vol. 27, 1901, p. 481, 502) states that tbe oxi- 
dizing ferments are able to withstand temperatures between 60° and 65 °C. for 
a long time, but are destroyed after a short exposure to 76 °C. The lipase, or 
fat-splitting ferment, withstands one hour’s heating at 60° C., or 62° for a 
short time: is weakened at 63°, and destroyed at 64°C. The proteolytic fer- 
ment withstands one hour’s heating at 60° or half an hour at 65°C. The amy- 
lase withstands one hour at 60° and is only destroyed at 75° C. See also Kastle 
and Roberts' article No. 10, p. 307, this bulletin. 
