SPECIFIC GRAVITY. 17 



the plummet. This having been determined, the spe- 

 cific gravityof a milk may be found by immersing the 

 plummet in it, and noting the loss in weight, which, 

 divided by the loss in pure water, gives the specific 

 gravity. 



The pyknometer or specific gravity bottle furnishes a 

 means of accurately determining specific gravity and is 

 especially suitable when only a small amount of liquid 

 is available. It consists of a small flask provided with a 

 finely perforated glass stopper. The flask is weighed, 

 first alone, then filled with waterat6o°F., then with the 

 milk at the same temperture. In filling the flask the 

 liquid is first brought to the proper temperature, the 

 bottle completely filled, the stopper inserted and the 

 excess, forced out through the perforation and around 

 the sides of the stopper, removed by bibulous paper. 

 The weight of milk divided by that of an equal bulk 

 of water gives the specific gravity. 



TOTAL SOLIDS. 



These are determined by evaporation in a shallow, 

 flat-bottomed platinum or porcelain dish from 7 to 8 cm. 

 in diameter. The milk must be spread evenly in a thin 

 layer. If the ash is also to be determined, about five 

 grams should be accurately weighed in the dish, evap- 

 orated rapidly to appai-ent dryness over the water-bath 

 and the heating continued in the water-oven until the 

 weight becomes practically constant, which will require 



