1824.] Philosophical Transactions for 1823, Part II. 145 



ments of temperature, there can be no doubt that the denser the 

 vapour, or the more difficult of condensation the gas, the greater 

 will be its power under changes of temperature as a mechanical 

 agent: thus carbonic acid will be much more powerful than 

 muriatic acid. In the only experiment which has been tried 

 upon it, its force was found to be nearly equal to that of air 

 compressed to -}-$ at 12° F. and of air compressed to -^ at 

 32°, making an increase equal to the weight of 13 atmospheres 

 by an increase of 20 of temperature ; and this immense elastic 

 force of 36 atmospheres being exerted at the freezing point of 

 water.* 



" In applying the condensed gases as mechanical agents there 

 will be some difficulty ; the materials of the apparatus must be 

 at least as strong and as perfectly joined as those used by Mr. 

 Perkins in his high pressure steam engine : but the small differ- 

 ences of temperature required to produce an elastic force equal 

 to the pressure of many atmospheres, will render the risk of 

 explosion extremely small ; and if future experiments should 

 realise the views here developed, the mere difference of temper- 

 ature between sunshine and shade, and air and water, or the 

 effects of evaporation from a moist surface, will be sufficient to 

 produce results, which have hitherto been obtained only by a 

 great expenditure of fuel. 



" I shall conclude this communication by a few general ob- 

 servations arising out of this inquiry. 



" There is a simple mode of liquifying the gases, which at 

 first view appears paradoxical, namely, b\j the application of heat ; 

 it consists in placing them in one lea; of a bent sealed tube con- 

 fined by mercury, and applying heat to ether, or alcohol, or 

 water, in the other end. In this manner, by the pressure of the 

 vapour of ether I have liquified prussic gas and sulphurous acid 

 gas, the only two on which I have made experiments; and these 

 gases in being reproduced occasioned cold. 



" There can be little doubt that these general facts of the 

 condensation of the gases will have many practical applications. 

 They offer easy methods of impregnating liquids with carbonic 

 acid and other gases, without the necessity of common mecha- 

 nical pressure. 



" They afford means of producing great diminutions of tem- 

 perature, by the rapidity with which large quantities of liquids 

 may be rendered aeriform ; and as compression occasions similar 

 effects to cold, in preventing the formation of elastic substances, 



• " Since this paper was read, Mr. Faraday has ascertained that the vapour of am- 

 monia at 32° everts an elastic force equal to that of an atmosphere compressed to 



1 . 10 



— ; and at 50° to that of an atmosphere compressed to — : and that the vapour of ni- 



trous oxide at 32° has an elastic force equal to that of an atmosphere compressed to 

 tj-; and at 45° to an atmosphere compressed to — - nearly." 



New Series, VOL. VI I. k 



