1824.] On the Liquefaction of Gases. 127 



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 appa- 

 ratus, have been equal to many atmospheres, but that being 

 condensable, 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 re- 

 ferred to in Thomson's ' System,' first edition, i. 405, and other 

 editions ; Henry's ' Chemistry,' i. 237 ; Accum's ' Chemistry/ i. 

 310; Murray's * Chemistry,' ii. 73; and Thenard's 'Traite* 

 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, mu- 

 riatic acid gas, 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 experiments of Guy ton de Morveau, ' Ann. de Chimie,' xxix. 

 291, 297. Thomson states the result of liquefaction at a tem- 

 perature of 45, without referring to the doubt, that Morveau 

 himself raises, respecting the presence of water in the gas ; but 

 Murray, Henry, and Thenard, in their statements notice its 

 probable presence. Morveau's experiment was made in the 

 following manner : A glass retort was charged with the usual 

 mixture of muriate of ammonia and quick-lime, the former 

 material being sublimed, and the latter carefully made from 

 white marble, so as to exclude water as much as possible. The 

 beak of the retort was then adapted to an apparatus consisting 

 of two balloons, and two flasks successively connected together, 

 and luted by fat lute. The balloons were empty ; the first flask 

 contained mercury, the second water. Heat was then applied 

 to the retort, and the first globe cooled to 21*25 C. ; aqueous 

 vapours soon rose, which condensed as water in the neck of the 

 retort, and as ice in the first balloon. Continuing the heat, 

 ammoniacal gas was disengaged, and it escaped by the last 

 flask containing water, without anything being perceived in the 



