of Iota! Solids.—Use a flat porcelain or aluminium dish,
,-, «., 10 ,-i ii; .iuiM-t'T. ami add 10 to 15 gin of white sand. Heat the dish
,,vl /.^j »i( ^...,,.,T.i;,! vu'iiiht at KM.')3, then add about 5 gin of milk, cover and
r,'rtV^h * (',r , j i ;, v.< if milk to the weighed <li*h and sand and calculate the
u ,'jfc-hT *->''•;' t}..' nu.'4-ifn- privity. Dry at 100° until the weight is constant.
O^nl'm *» d*>if-.u!or :irid \vt.-jgh'rapidly. Calculate the per cent of solids.
Ash.-—Tho ii>h doos not represent all of the inorganic constitu-
ent,* of in ilk in their original combinations because certain
fhrniir- tak> place during the burning of the organic matter.
HM- :i»ii ^huuld m>t l>e heated to a temperature higher than
wji? :t> tlif dilorides of sodium and potassium might be vola-
tilized at a liiglter temperature. Nitric acid may be added to
aid in oxidizing the organic matter.
of Ash.—Weigh accurately a flat platinum or porcelain
di>h h'liiir.a: J5 to 30 ec\ Add 20 ec of milk of known specific gravity or
obtain riif ui-igli! l»y direct weigliing. In the latter case the dish must be
fi»Ye'fvd U'tV>?v aiul ufkT adding the milk. Add five drops of concentrated
fistrh' -ii-id ,i!«-d t'vapnrate to tlryness on the steam bath, then ignite at a
tt<ni|»rnitinv ju#t }->e3ow redness until white. Cool in a desiccator and
\vrigh. i'aifulate the pc^r cent of ash.
Fat.—-Tho fat contained in milk is usually given, more con-
jsidmttion than any other constituent, since milk is bought and
jsokl largely tin the basis of its fat content. To some extent this
is uufurtunato as it has tended to underrate the other constitu-
ents, which may be of equal or greater value as food.
"Paper Coif1 Method.—In this method the milk is absorbed
on porous fat-free paper and dried. In this condition the fat
I< easily and quickly extracted as most of it is on the surface of
the paper and it is thus somewhat separated from the proteins
present. Ether is generally used to extract the fat. This must
be anhydrous in order to avoid dissolving some of the milk sugar
present. Petroleum ether is sometimes used but it lias the
disadvantage of dissolving fats more slowly than ordinary ether.
Tho fat extractor, shown in Fig. 41, page 146, is used for the
deU'rinination. if other forms of extractors employing cork
stoppers are used the corks must be made free from ether-soluble
waxes and resins by previous extraction with ether and they
must fit tightly enough to prevent the escape of any considerable
amount of ether.