The following may be taken as being the average composi-
tion of good yellow and black railway grease : —



Water

Tallow . . . . ,

Palm oil

Soap (containing 30 % water)

Petroleum reSiduum

Soda ash ....
Yellow.
Per cent.
Black.
Per cent


37


25


30 . ;

lO-S

21


17

4
13-5


1-5


40-0



Grease used on the German railways has the following
composition : —







Per cent.
Tallow




24' 6


Palm-oil




9-8


Rape-seed oil




I-I


Soda.
S-2


Water •.
59-3
loo-o


strian Grease: —








Tallow.
Olive Oil. Old Grease


For winter


100


20 13


•For spring and autumn


100


10 10


For summer


100


. 1 10



Tallow.
Australian mutton tallow and Russian tallow are much used
in the manufacture of grease, and in judging its quality it
becomes necessary to know the amount of moisture, free fatty
acids, suspended matter (mineral and organic), the total fatty
acids, together with the determination of the melting and con-
gealing points of the sample, and also of the total fatty acids.
Estimation of Moisture. — Weigh into a tared beaker,
supplied with a glass rod, 10 grms. of the fairly averaged



232 RAILWAY GREASE.
sample, dry in an oil bath or air oven for one hour, at a
temperature of iio° C, allow to cool and reweigh; replace
in the oil bath or air oven for another hour, cool, and again
weigh; if there is no considerable diiference between this
and the last weighing the loss is taken as moisture. The
normal amount of moisture in tallow ranges from 0*5 to 2 per
cent.
