■478 
Deerfoot Farm Centrifugal Dairy. 
this fact is the reasonable, although as }et unproven, view that 
the butter fats exist in a certain relation in the globules, and it 
is this natural relation which produces the so-called grain of 
butter : when this relation is disturbed by overworking the 
butter, this grain, so much desired, becomes lost. In the larger 
globules this arrangement is coarser and more distinct, as shown 
in the aggregate butter, than in the smaller globules. This 
view of the relations of the fats is, however, disputed by some, 
as it is claimed that in oleomargarine factories butter and tallow 
melted together and allowed to fall in a small stream into ice 
water takes on a condition which gives to the completed product 
a fine grain of high quality. 
The fat globules again have a lower specific gravity than the 
fluid in which they float ; they are invested in a membrane, 
j)robably animal in its origin, which is heavier than the fatty 
contents. Hence, as the different specific gravities of the enve- 
lope and the contents vary greatly as the diameters change, 
the large globules are specifically much lighter in relation to the 
fluid in which they float than are the smaller globules, and they 
accordingly rise with far greater rapidity towards the surface. 
In addition, these form-elements of the milk have a different 
specific heat than the unformed fluid elements, and accordingly 
•quick changes of temperature do not warm or cool the fat 
globules, and thus affect their specific gravity, in the same pro- 
portionate time as the fluid portion is warmed and cooled. 
Millon and Commalle distinguish a casein suspended in milk, 
and another dissolved in it. This relation appears to have been 
generally overlooked by students on milk, yet I am disposed to 
believe that the microscope discovers many granules of this 
casein suspended in skim-milk, and these are often, perhaps, 
confounded with fat globules of such small size that their enve- 
lope loads them down so that their tendency is to remain in sus- 
pension, or to fall rather than to rise. An analysis of the scum 
which collects upon the walls of the drum of the centrifugal 
machine, as analysed by Lawrie and Terry, shows casein there 
at the point of greatest pressure to the amount of 25 '49 per cent. 
As casein has a greater specific gravity than the other constitu- 
ents of milk (1280, according to Professor Goessman, in a private 
letter), all that casein which has form would naturally seek the 
circumference when put under the influence of centrifugal force. 
Moreover, if skim-milk be taken and diluted with a little water, 
the microscope will detect more granules in the lowermost layers, 
after it has stood quietly for some time, than in the upper por- 
tions. It is but proper to state, however, that analyses made for 
the purpose of this paper of the skiin-milk from the interior and 
exterior of the milk as occupying the machine, not, however, 
