1 Fes., 1899.] QUEENSLAND AGRICULTURAL JOURNAL. 119 
MILK TESTING. 
RAPID FAT DETERMINATION PROCESSES. 
Tn rapid methods for determining fat in milk, which are so universally used 
at the present day, are all, for the most part, improvements on the Lactocrite, 
which was the first of these methods, and, although not in common use at any 
time, was the original test, employing, as do all the present-day methods, 
centrifugal force. 
The idea in all these processes is to dissolve the casein of the milk by a 
fairly strong acid. While this action is going on, there is necessarily a great 
rise in temperature, the liquid becoming very hot. This rise of temperature 
causes the fat to liquify, and, when submitted to centrifugal force, it all comes 
to the surface, and can be measured in the graduated neck of the test bottle. 
BABCOCK’S METHOD ; 
was on the same principle, and the next test to be brought out. With this 
machine, sulphuric acid of a certain strength (specific gravity 1:82) is used, 
and the bottles, after been turned in the machine for several minutes, are filled 
up to the neck with hot water, being again whirled for a couple of minutes, 
when the fat may be read off. 
Another method is the Leffmann Beam test, but, as an accurate descrip- 
tion of one process will tend to serve for the lot, we will take Dr. Gerber’s 
butyrometer as an example, and describe this process. It has been found, 
when using sulphuric acid, that, owing to the great rise in temperature when 
mixed with the milk, some of the fat, with milk sugar, gets charred to a black 
substance which consequently interferes with obtaining accurate results. ‘To 
do away with this, amyl alcohol has been found to be the best substance. So 
that in one or two methods we find this substance always added. 
The Gerber test undoubtedly finds most favour in England and Germany, 
at least at the present time, and, indeed, we may say is decidedly the handiest 
and quickest method of testing for milk fat, and probably the best of all 
present-day volumetric tests. 
To perform this test is an extremely simple matter, and it may be 
performed with great accuracy after a few trials, with an ordinary amount of 
care. 
Sampling the milk is of the greatest importance, and if not properly done 
it is useless to perform the test, as then it would be both waste of time and 
material. 
‘The milk to be sampled should be thoroughly mixed by tilting (if only a 
small quantity), say an individual cow’s milk, from pail to pail; and when 
satisfied that the cream is well distributed throughout the whole, a sample may 
be taken. Milk is best sampled when warm from the cow. 
MAKING THE TEST. 
The essentials for the test are pipettes of tubes for measuring the acid and 
milk of the following capacities :— 
10 cubic centimetres for acid, 
IL i 3 milk, 
1 5 3 amyl alcohol. 
(2) Test bottles fitted with rubber corks. 
(3) Chemicals for test. 
The sulphuric acid used should have a specific gravity of 1°82, but may 
be varied a little from this strength without affecting the accuracy of the 
test. 
MEASURING THE QUANTITIES. 
First of all, 10 c.c. of the sulphuric acid is drawn up in the pipette. A 
safety pipette as illustrated is best for this purpose, as ifi saves very often a 
blistered mouth, and perhaps, at the same time, a certain amount of strong 
language. 
