232 Mr. Faraday on the Liquefaction of Gases. 



might the latter ; for it cannot be doubted but that in similar cir- 

 circumstances, the elastic force of carbonic acid would far sur- 

 pass that of water. Count Rumford says, that the gunpowder 

 made use of, when well shaken together, occupied rather less 

 space than an equal weight of water. The quantity of residuum 

 before referred to, left by a given weight of gunpowder, is not 

 mentioned, so that the actual space occupied by the vapour of 

 water, carbonic acid, &c, at the moment of ignition, cannot be 

 inferred ; there can, however, be but little doubt that when per- 

 fectly confined they were in the state of the substances, in M. 

 Cagniard de la Tour's experiments*. 



When allowed to remain a few minutes, or even seconds, the 

 expansive force at first observed, diminished exceedingly, so as 

 scarcely to surpass that of the air in a charged air-gun. Of course 

 all that was due to the vaporization of water and some of the other 

 products would cease, as soon as the mass of metal had absorbed 

 the heat, and they would concrete into the hard substance found 

 in the cylinder : but it does not seem too much to suppose, that so 

 much carbonic acid was generated in the combustion, as would, 

 if confined, on the cooling of the apparatus, have been equal to 

 many atmospheres, but that being condensible, a part became 

 liquid, and thus assisted in reducing the force within, to what it 

 was found to be. 



Ammonia. — I find the condensation of ammoniacal gas referred to 

 in Thomson's System, first edition, i. 405, and other editions ; Henry's 

 Chemistry, i. 237 ; Accum's Chemistry,!. 310; Murray's Chemistry, 

 ii. 73. ; and Thenard's Traitc de Chimie, ii. 133. Mr. Accum refers 

 to the experiments of Fourcroy and Vauquelin, Ann.de Chimie, 

 xxix. 289, but has mistaken their object. Those chemists used 

 highly saturated solution of ammonia, see pp. 281, 286, and not 

 the gas ; and their experiments on gases, namely, sulphurous acid 

 gas, muriatic acid ~as, and sulphuretted hydrogen gas, they state 

 were fruitless, p. 287. "All we can say is, that the condensation 

 of most of these gases was above three fourths of their volume." 



Thomson, Henry, Murray, and, I suppose, Thenard, refer to the 

 * See vol. xv. p. 145, of this Journal. 



