172 



DR. FARADAY ON THE LIQUEFACTION AND SOLIDIFICATION OF 



ginal objects of my pursuit, I have added six substances, usually gaseous, to the list 

 of those that could previously 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 tension of vapour cannot (because of the difficul- 

 ties respecting the use of thermometers and the apparatus generally) be considered 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 remarTis respecting the Condensation of Gases. 

 By Michael Faraday, Esq. 



Received February 20, — Read February 20, 1845. 



Nitrous oxide. — Suspecting the presence on former occasions of nitrogen in the 

 nitrous oxide, and mainly because of muriate in the nitrate of ammonia used, I pre- 

 pared 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 remained for some days in well-closed bottles in 

 contact with a little water, I condensed it in the manner already described, and 

 when condensed I allowed half the fluid to escape in vapour, that as much as possible 

 of the less condensable portion might be carried off. In this way as much gas as 

 would fill the capacity of the vessels twenty or thirty times or more was allowed to 

 escape. Afterwards the following series of pressures was obtained : — 



