114 On the Liquefaction and Solidification [1844. 



55*5 grains, then a cubic inch of the liquid would weigh 218*6 

 grains. This gives its specific gravity as 0*866. When first 

 condensed, I estimated it as nearly 0*9. 



Cyanogen is a substance which yielded on different occasions 

 results of vaporous tension differing much from each other, 

 though the substance appeared always to be pure. The fol- 

 lowing are numbers in which I place some confidence, the 

 pressures being in atmospheres of 30 inches of mercury, and 

 the marked results experimental *. 



Fahr. 







8-5 



-10 



15 



-20 



22-8 

 -27 

 -32 

 34-5 



Ammonia. This body may be obtained as a solid, white, 

 translucent, crystalline substance, melting at the temperature 

 of 1 03 below ; at which point the solid substance is heavier 

 than the liquid. In that state the pressure of its vapour must 

 be very small. 



Liquid ammonia at 60 was allowed to expand into ammo- 

 niacal gas at the same temperature ; one volume of the liquid 

 gave 1009*8 volumes of the gas, the barometer being at the 

 .pressure of 30'2 inches. If 100 cubic inches of ammoniacal 

 gas be allowed to weigh 18*28 grains, it will give 184*6 grains 

 as the weight of a cubic inch of liquid ammonia at 60. Hence 

 its specific gravity at that temperature will be 0*731. In the 

 old experiments I found by another kind of process that its 

 specific gravity was 0*76 at 50. 



The following is a Table of the pressure of ammonia vapour, 

 the marked results, as before, being those obtained by experi- 

 ment : 



See Bunsen's results, Bibliotheque Universelle, 1839, xxiii. p. 185. 



