Dr. Muter 1 gives 

 oils at 37.7 C. 



DAIRY PRODUCTS. 43 



the following table of the specific gravity of various 



METHOD EMPLOYED IN CHEMICAL DIVISION. 



When convenient the determination of specific gravity is not made 

 until a number of samples is on hand. Each determination is made in 

 duplicate. The picuometers, holding about 25 grams, are filled with the 

 filtered fat, at as low a temperature as possible, and placed in a flat dish 

 filled with water as nearly to the tops of the flasks as possible. The 

 picnometers used should all be of the same height. The stopper has 

 a capillary perforation for the escape of the oil as the temperature rises. 

 It' the picnometers are not furnished with thermometers of their own, a 

 tlelicate.thermometer is suspended in the water surrounding them. The 

 water-bath is slowly warmed and gently but constantly stirred until the 

 temperature reaches 40 0. It is kept at this temperature for fifteen or 

 twenty minutes, until the fat has taken on the same temperature as the 

 water. The picnometers are then carefully cleaned and dried, and, after 

 cooling to the temperature of the balance-room ^ are weighed. This 

 method is somewhat tedious when only one determination is to be made, 

 but where many samples arc to bo examined it is sufficiently speedy. 

 In respect of accuracy it leaves nothing to be desired. 



TEMPERATURE AT WHICH SPECIFIC GRAVITY IS STATED. 



Different analysts select different temperatures for determining spe- 

 cific gravity. It would be well to have some agreement on this point- 

 to avoid confusion. 



Since the specific gravity determined at any temperature can be easily 

 calculated for any other given temperature, I suggest that it might be 

 well to express all specific gravities in terms of water at 4 0. 



THE MELTING POINT OF FATS. 



The fats pass rather slowly from the semi-solid state, which is their 

 natural condition at ordinary temperatures, to complete fluidity. It is, 

 therefore, difficult to determine accurately the exact temperature at 

 which they melt. 



1 A lieu, op. cit., p. 15, foot-note. 



