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 lie 

 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. Estconrt 

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

 balance is suspended in the test tube (l;|iti. 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 Hd 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 : — 



