1 
American Milk- Condensing Factories. 133 
" 1 am assured from what I see in your writings on the 
subject of milk as applied to the making of butter and cheese 
.that you fully concur in all I have said in relation to the 
subject. We both realize that it is for the want of a full under- 
standing of the delicate character of milk that so many have 
failed in producing a good article either of cheese or condensed 
milk." 
i'leanintj the Vacuum-Pan. — After condensing the milk and 
drawing from the vacuum-pan, the pan must be thoroughly 
cleaned. For this purpose there is a man-hole, by which a person 
can enter the pan and do the work with brushes, sand-paper, and 
water. I am told that for a long time Mr. Borden experienced 
considerable difficulty in having the pans properly cleaned, as 
the milk during the process of condensing would adhere to the 
metal and bake or harden into a crust. After a while it was dis- 
covered that by oiling the metal on the inner surface of the 
pan this difficulty could be obviated. 
The discovery was made through merely accidental circum- 
stances, and from observing an old housewife " grease the pot," 
preparatory to making " minute pudding." On applying the 
principle to the vacuum-pan it was found to prevent the milk 
adhering to the metal, and a patent was at once secured upon it. 
Introducing a little water in the pan just before drawing in the 
milk effects the same object. This is one of the secrets of the 
condensing business. 
Gauging the Milk. — Difficulty is sometimes experienced in 
determining when the milk is reduced to the proper consistency. 
In regulating this, samples of condensed milk are drawn from 
the pan, and the amount of water removed is judged from its 
specific gravity and appearance on cooling. 
Errors not unfrequently occur in carrying the condensing pro- 
cess too far, especially with persons who have not a correct eye, 
or who may become a little careless at times. I am told that a 
I gauge placed in the pan is an important aid in this matter. The 
quantity of milk to go into the pan beina: noted, the gauge indi- 
I cates the amount and rapidity of the evaporation, and thus renders 
I important assistance in regulating this essential point in the 
process ; for it must be observed that, if the reduction is carried 
\ beyond 75 per cent., there is not only a loss in weight, but the 
consistency not being uniform will have its influence on sales ; 
and the quality is also liable to be deteriorated. 
The plain condensed milk has the same amount of water 
1 removed, and is treated in the same way as that which has 
been described, except that no sugar is used in its manufacture. 
It is not put up in sealed cans, but will keep sound for several 
