1*22 HYDROSTATICS. 



most requisite circumstance, and diminish the so- 

 lidity, which necessarily renders the instrument 

 still more accurate. 



Proof-spirit consists [of pure spirit with a little 

 water; that is, such as, when poured on gunpowder 

 and set on fire, will burn all away; and permit the 

 powder to take fire and flash, as in open air. But 

 if the spirit be not so highly rectified, there will re- 

 main some water, which will make the powder wet, 

 and unfit to take fire. Proof-spirit of any kind 

 weighs seven pounds twelve ounces per gallon. 



The common method of shaking the spirits in a 

 phial, and raising a head of bubbles, to judge by 

 their manner of rising or breaking, whether the 

 spirit be proof or near it, is very fallacious. 



Syke's Hydrometer, represented Plate 25. fig. 4. 

 is that now used by the excise officers in collecting 

 the revenue. Weights are made to slide on the coni- 

 cal stem below the ball ; and the graduation of the 

 upper stem shows the specific gravity of the liquor. 



Table of Specific Gravities. 



Distilled water, 1.000 



Sea water, - 1.026 



Water of the Dead Sea, ... 1 .240 



Crude platina, in grains, - 15.602 



Platina, purified and fused, - 19.500 



hammered, .... 20.377 



drawn into wire, - 21.042 



laminated, .... 22.069 



Pure gold, cast, 19.258 



hammered, - 19-362 



Standard gold, 17-486 



hammered, - - - 17-589 



Mercury, - 13.568 



