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TENTHi ANNUAL. CONVENTION
Variations in the Amount of Casein in
Cows' Milk and the Operation
of the Casein Test.
Prop. T. B. Hart, State Chemist, U. W.
There is a getieral belief anion- dalirynmen  and sonile
dlairs chemists that casein an(l fat are present in mmilk in
constant relative proportionls. That g iven the  perCenltage
of fat in milk, the percentagre of casein can be directly
calculate(l b)v rule. The rule is to l)e applied espeecially to
milks ranging- from three to four and one-half per cent of
fat all(n is stated as follows: To find the per cent of casein
in milk when the per cent of fat is known. subtract three
from the per centof fat in milk, multiply the result b)- 4
and add the result to 2.1. The limitations placed oin the
rule as applicable to milks containing  but from  three to
four and one-half per cent of fat led the writer to in(JUire
how applicable to milks of higher fat content. IIill-i as
early as 1890, showe(l that in in(livi(lual cows the propor-
tion between fat and casein is wi(lelv different. Hle how-
ever obscure(l this iml)ortant fact b v conclusions based on
avcrages of manv milk analyses. His conclusiomi was that
normal milks, whether rich or poor, have on aln average
one-fourth as much casein as total solids, though lie fur-
ther savs that single salimples may depart widely from this
stan(lar(l.
f    Fourth Anmmi. Report. V't. Agr. FJxpt. Sta.
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