CURING BUTTER IN THIS COUNTRY AND ABROAD. 203 



(Minvspdndingly, thv. saiiu; law aifccts sliriiikai^c In falling from 

 liigh to low, water shrinks little, iat luueh, and the specitlc gravity 

 thus becomes more nearly alike; hence the fat rises slowly at a 

 low and unvarying temperature. From the fact of water being 

 a better conductor, it feels the efCect of heat or cold more readily 

 than the fat in cream ; thus, when the temperature is rising, 

 the (Urierence of specific giavity is diminished, — when falling, 

 increased. At the same temperature the difierence is so little 

 as to give only a very slow motion to tlie cream ; but any serious 

 alteration of temperature, from the ellect of either heat or cold, 

 will give, in the case of the latter, a hurried ascent, in the former, 

 a scarcely perceptible one. And as some particular fancy as to 

 a, particular heat or depth has become firmly fixed in the mind 

 of the dairyman, this accelerated ascent of cream in a falling 

 temjjcrature has rarely in practice been turned to the best 

 account. 



As to depth, it is evident that cream will rise quickest through 

 a small depth of milk ; but still no particular depth can, without 

 a due regard to volume and temperature, be set down as the 

 correct one. For instance, two vessels of milk of even depth 

 at 80° being set in a room at 50°, but with one of them previously 

 cooled to the same temperature as the room, that one will not 

 throw u]) the cream so rapidly or so perfectly, because it received 

 no benefit from the difference of specific gravity arising from the 

 falling temperature. But if it had been allowed to stand until 

 the cream ceased to rise, and then re warmed and set at 50°, or 

 alternatively, — without being again warmed to the original tem- 

 })eiiiture, — it had been set in a room 20° colder, so as to allow a 

 farther fall of temperature, as good result would have Ijeen got 

 as from the other vessel. Shallow setting will throw up best in 

 a warm room ; because in a cold one it goes through its fall oi 

 temperature so quickly that the cream has not time to rise, and, 

 as before shown, a high temperature, when unvarying, tends to a 

 quick rise. Milk spoils sooner when kept warm ; yet milk two 

 inches deep at 65° will throw the cream quickly and almost 

 perfectly ; but it would not do so at 50°, because the milk, falling 

 quickly to the room temperature, loses the benefit of the differ- 

 ence of specific gravity before the cream is all u\). At 65° it 

 will rise through 2 inches perfectly before souring begins ; 

 but at 60° souring would begin before the cream was all up, and 

 both quantity and quality would suffer. But if the deeper 

 vessel were set at 50° the result would be different, the greater 

 depth prolonging the cooling, so that the cream would be all up 

 before the temperature of the room was reached. Thus it is 

 easily seen that both deep and shallow setters may be right, if 

 only the temperature through the range of which the milk has 

 to fall in cooling be properly arranged. Larger or smaller 



