1844.] of Bodies generally existing as Gases. 117 



olefiant, nitric oxide, carbonic oxide, fluosilicon, hydrogen, 

 and nitrogen gases were submitted to pressures, rising up to 

 220 atmospheres in the case of the last two ; but this was in 

 the depths of the sea where the results under pressure could 

 not be examined. Several of them were diminished in bulk in 

 a ratio far greater than the pressure put upon them ; but both 

 M. Cagniard de la Tour and M. Thilorier have shown that 

 this is often the case whilst the substance retains the gaseous 

 form. It is possible that olefiant gas and fluosilicon may have 

 liquefied down below, but they have not yet been seen in the 

 liquid state except in my own experiments, and in them not at 

 temperatures above 40 Fahr. The results with oxygen are so 

 unsteady and contradictory as to cause doubt in regard to those 

 obtained with the other gases by the same process. 



Thus, though as yet I have not condensed oxygen, hydrogen, 

 or nitrogen, the original objects of my pursuit, I have added six 

 substances, usually gaseous, to the list of those that could pre- 

 viously be shown in the liquid state, and have reduced seven, 

 including ammonia, nitrous oxide, and sulphuretted hydrogen, 

 into the solid form. And though the numbers expressing ten- 

 sion of vapour cannot (because of the difficulties respecting the 

 use of thermometers and the apparatus generally) be con- 

 sidered as exact, I am in hopes they will assist in developing 

 some general law governing the vaporization of all bodies, and 

 also in illustrating the physical state of gaseous bodies as they 

 are presented to us under ordinary temperature and pressure. 



Royal Institution, Nov. 15, 1844. 



NOTE. ADDITIONAL REMARKS RESPECTING THE CONDENSATION OF 



GASES. 

 [Received February 20, Read February 20, 1845.] 



Nitrous Oxide. Suspecting the presence on former occa- 

 sions of nitrogen in the nitrous oxide, and mainly because of 

 muriate in the nitrate of ammonia used, I prepared that salt in 

 a pure state from nitric acid and carbonate of ammonia pre- 

 viously proved, by nitrate of silver, to be free from muriatic 

 acid. After the nitrous oxide prepared from this salt had re- 

 mained for some days in well-closed bottles in contact with a 



