FIFTH ANNUAL YEAR BOOK — PART IV. 235 



CARE OF MILK ON THE FARM. 



PROFESSOR BOUSKE, AMES. 



Mr. President, Ladies and Gentlemen— \ think you are unfortunate in 

 having to have a substitute for Professor Curtiss. 



I will just speak about a tew of those things that come up in taking care 

 of the milk on the farm, because that is something that is always of interest 

 at this season of the year. It is something on which a good deal can be 

 said, and for that reason I will only take up a few features that are of inter- 

 est at the present time of the year, viz: the freezing of milk, the eflfect of 

 freezing upon milk, and the effect of keeping milk in the barn, in houses and 

 in the kitchen. 



When milk freezes it seems to do so in a different manner some way from 

 the way in which water will freeze. Of course the first ingredient in milk to 

 freeze is the water and, if the freezing takes place slowly, as it usually does 

 because people seldom leave milk exposed to intense cold where it will freeze 

 rapidly, if frozen in such a place slowly, water will crystalize into little 

 crystals of ice, and if this goes on slowly you will finally have a kind of 

 slush, looking a good deal like a mixture of snow and milk. The water 

 freezing first forms these crystals of ice. Usually, I think, they are rather 

 apt to be needle shape, and the other constituents of the milk hardening 

 later. It is a question whether we could say that the casein and butter fat 

 freezes. Butter fat becomes hard sometimes. When the milk is freshly 

 drawn it is still warm and the butter fat is in liquid condition, and remains 

 in a liquid condition even at seventy degrees, but somewhat below that it 

 hardens; we might also say freezes or congeals. As this freezing goes on, 

 this crystalization of water into ice, the other constituents in the milk are 

 crowded' more together. The milk consists mostly of water, about eighty- 

 seven per cent being water and this water gathers together into lumps, and 

 between these lumps or crystals of ice are found the butter fat or casein, so 

 in that kind of freezing the milk is not as homogenous as it is when not 

 frozen. Of course any large quantity of it would contain the same 

 portion of those different ingredients, but if we were to pick out little bits of 

 milk you might get mostly ice and mostly constituents not water, that is 

 casein and fat. 



If this freezing repeats itselt, that is the milk thaws itself, then freezes 

 and thaws again, the butter will appear upon the surface of the milk. I 

 think a good many of you have noticed butter on the strainers when a quality 

 of milk has been run through in the winter. I have noticed it very often my- 

 self. Then I have noticed that in the tempering vat, the kind of vat we 

 used to use some years ago when you hold the supply of milk for separation 

 and where it is tempered before it runs in, very often in those vats you will 

 notice the melted butter on the surface of the milk. That is not butter 

 churned out of the milk by agitation of the milk on its way to the creamery; 

 it is butter that has been produced by repeated freezing and thawing of the 

 milk. This is even m; re apparent with c:eam. This fall I saw a little jar 

 of cream which was ripened and then left in a cold place where it froze. 

 Upon thawing, butter appeared in the cream, a big chunk of butter just the 

 same as though it had been churned. This happened with only one freezing. 



