Mr. Faraday on the Liquefaction of Gases. 235 



Notwithstanding Fourcroy's objection, there can be but little 

 reason to doubt that Monge and Clouet did actually condense the 

 gas, for I have since found that from the small elastic force of its 

 vapour at common temperatures, (being equal to that of about 

 two atmospheres only*) a comparatively moderate diminution of 

 temperature is sufficient to retain it fluid at common pressure, or 

 a moderate additional pressure to retain it so at common tempe- 

 rature ; so that whether these philosophers applied cold only as 

 Fourcroy mentions, or cold and pressure, as stated by the other 

 chemists, they would succeed in obtaining it in the liquid form. 



Chlorine.' — M. de Morveau, whilst engaged on the application of 

 the means best adapted to destroy putrid effluvia and contagious 

 miasmata, was led to the introduction of chlorine as the one 

 most excellent for this purpose ; and he proposed the use of phials, 

 containing the requisite materials, as sources of the substance. 

 One described in his Traite des Moyens de desinfecter Vair (1801), 

 was of the capacity of two cubical inches nearly; about 62 grains 

 of black oxide of manganese in coarse powder was introduced, 

 and then the bottle two-thirds filled with nitro-rnuriatic acid ; it was 

 shaken, and in a short time chlorine was abundantly disengaged. 

 M. Morveau remarks upon the facility with which the chlorine is 

 retained in these bottles ; one, thus prepared, and forgotten, when 

 opened at the end of eight years, gave an abundant odour of 

 chlorine. 



I had an impression on my mind that M. de Morveau had pro- 

 posed the use of phials similarly charged, but made strong, well 

 stoppered, and confined by a screw in a frame, so that no gas 

 should escape, except when the screw and stopper were loosened; 

 but I have searched for an account of such phials without being 

 able to find any. If such have been made, it is very probable 

 that in some circumstances, liquid chlorine has existed in them, 

 for as its vapour at 60° F. has only a force of about four atmo- 

 spheres'!", a charge of materials might be expected frequently to 

 yield much more chlorine than enough to till the space, and 

 saturate the fluid present; and the excess would of course take 

 the liquid form. If such vessels have not been made, our present 

 * Philosophical Transactions, 1823, p. 1[)2. t Ibid. p. 198. 



