SPECIFIC GRAVITY. 85 



will sink at 145 F., and beads of 896- specific gravity 

 will sink at 132 F. As a guide to the gravity it may be 

 assumed that a difference of 1 F. in the sinking temperature 

 indicates -30 actual density, equal to about '35 per cent, of 

 insoluble fatty acids. 



The application of that well-known and delicate instru- 

 ment for the determination of specific gravities, Westphal's 

 balance, to butter analysis, has been suggested by C. Estcourt 

 (Chemical News, vol. xxxiv. No. 890). "The bulb of the 

 balance is suspended in the test tube (IJin. by 5 in.) which 

 contains the fat. This test tube is immersed in a metal tube 

 containing paraffin (any other substance with a high boiling 

 point will do), which is closed at the bottom. This tube is 

 fastened securely by luting, etc. on to the lid of a small water- 

 bath of suitable size, which has an outlet for steam, to which 

 a glass tube can be attached and a tube at the side to indi- 

 cate the quantity of water in the bath." These precautions 

 and arrangements are necessary in order to avoid the conden- 

 sation of steam on the beam of the balance. 



When the temperature of the paraffin indicates 206 F., 

 the weights on the balance are exactly adjusted, and the 

 specific gravity is read off, when the temperature becomes 

 stationary, which, in Mr. Estcourt's instrument, takes place 

 at 208 F. 



The following results were thus obtained by Mr. Estcourt : 



Beef fat 860'0 



Mutton fat 860-6 



Lard, home rendered 862 '8 



Butter M 870-0 



Butter BB 8707 Calculated 



Equal weights of mutton fat and butter 865 -6 ... 865-0 

 Equal weights of beef and butter ... 8 65 '7 ... 865-8 

 Equal weights of lard and butter ... 865-8 ... 866-4 

 Dutch butterine 865-2 



