1 Mar., 1898.] QUEENSLAND AGRICULTURAL JOURNAL. 183 
To determine the reducing ratio of this skim milk, 100 gallons (the 
quantity of milk used in a number of experiments) was divided by 5}, giving 
a final proposed product of about eighteen and one-fifth gallons, which must 
include the cream admixture made at the finish of the process. The proportion 
of fat in this finished product should be 14%; per cent., which has its equi- 
valent in about five and one-fifth gallons of the heavy cream. Deducting this 
volume of heavy cream from the calculated volume of finished product, we have 
about thirteen gallons as the standard to which,the 100 gallons of skim milk is 
to be condensed by the freezing process. In other words, eighty-seven gallons 
of water in the milk are formed into ice, leaving an unfrozen balance of 
thirteen gallons of very thick milk, which represents in milk sugar, casein, and 
inorganic salts fully nine gallons of solids. The fat equivalent, represented 
by the five and one-fifth gallons of heavy cream, is adjusted in the final product 
to represent in a dilution with water three parts, and condensed milk one part, 
a proportion of 3,5, per cent. of milk fat; which is the normal proportion in an 
average good milk. 
The freezing closets having been properly refrigerated, the previously 
cooled milk, measuring 100 gallons, was put in the pan, the closet closed, and 
in due time the stirring apparatus was put in motion. After nine hours the 
whole bulk of milk was converted into a magma of ice crystals and milk 
sufficiently thick to form into hummocks. When run in the centrifugal, the 
thick milk measured about fifty gallons. An average sample of the snow-like 
ice, When melted and evaporated to dryness, gave ,%, per cent. of residue. The 
fifty gallons of thick milk was returned to the freezing closet, and in six 
and one-half hours it was a dense crystal mass, which, after centrifugal treat- 
ment, measured about twenty-five gallons. The ice contained 4/5; per cent. of 
solids. A third freeze of four and one-half hours and centrifugal extractions 
reduced the bulk of the milk to about thirteen gallons. The ice from this last 
freeze assayed 1,2; per cent. of solids. The total time both for freezing and 
extracting was about twenty hours with one freezing closet; but this time, 
with two closets, could bave been reduced from one-third to one-half. It will 
be noticed that the percentage of solids in the ice increases slightly as the milk 
becomes concentrated, due to adhering thick milk to the ice crystals. This 
tendency is overcome largely by increasing the speed of the centrifugal, 
particularly on the last freeze. 
A final step in the process was the admixture of the heavy cream in proper 
proportions with the concentrated fat-free milk. This final product or con- 
densed milk is a fair representative of milk minus the bulk of its water. It is 
free from cooked flavours, it has a milk aroma which is true to the milk from 
which it is prepared, and it mixes easily with water, forming milk trom which 
cream will separate as from untreated milk. 
The specific gravity is about 1:16, the colour is a creamy white, and the 
consistence is smooth, the milk pouring slowly. In taste it is bland and 
creamy, with a very pronounced sweet taste which is strictly normal, as will be 
found by diluting with water to original proportions. In keeping properties 
the new form of condensed milk is superior to whole milk, as the freezing 
temperature at which the milk is held is destructive of some forms of germ life 
common to milk, and the natural life of the preparation is prolonged by this 
partial sterilisation. 
A comparative statement of the use of unsweetened condensed milk, cream 
and whole milk, would be very instructive and valuable, but after careful 
inquiries it was found that accurate data could not be obtained, as unsweetened 
condensed milk is classified and shipped into New York as cream, and vice 
versi. 
The recorded figures show that cream is preferred by the public, and the 
judgment of experts is to the effect that there is a diminishing demand for 
condensed milk, which possibly can be attributed to cooked flavours, lack of. 
taste, and non-adaptability for cooking purposes, or dilution to normal milk. 
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