160 



DR. FARADAY ON THE LIQUEFACTION AND SOLIDIFICATION OF 



the baths I required during the whole time, produced by one supply of 220 cubic 



inches^. 



By the apparatus, and in the manner, now described, all the gases before condensed 

 were very easily reduced, and some new results were obtained. When a gas was 

 liquefied, it was easy to close the stop-cock, and then remove the condensing tube 

 with the fluid from the rest of the apparatus. But in order to preserve the liquid 

 from escaping as gas, a further precaution was necessary ; namely, to cover over the 

 exposed end of the stop-cock by a blank female screw-cap and leaden washer, and 

 also to tighten perfectly the screw of the stop-cock plug. With these precautions I 

 have kept carbonic acid, nitrous oxide, fluosilicon, &c. for several days. 



Even with gases which could be condensed by the carbonic acid bath in air, this 

 apparatus in the air-pump had, in one respect, the advantage ; for when the conden- 

 sing tube was lifted out of the batli into the air, it immediately became covered with 

 hoar frost, obscuring the view of that which was within ; but in vacuo this was not 

 the case, and the contents of the tube could be very well examined by the eye. 



Olefiant gas. — This gas condensed into a clear, colourless, transparent fluid, but did 

 not become solid even in the carbonic acid bath in vacuo ; whether this was because 

 the temperature was not low enough, or for other reasons referred to in the account 

 of euchlorine, is uncertain. 



The pressure of the vapour of this substance at the temperature of the carbonic 

 acid bath in air (— 103°Fahr.) appeared singularly uncertain, being on different 

 occasions, and with different specimens, 3'7j ^'7, 5 and 6 atmospheres. The Table 

 below shows the tension of vapour for certain degrees below 0° Fahr., with two dif- 



* On one occasion the solid carbonic acid was exceedingly electric, but I could not produce the effect again : 

 it was probably connected with the presence of oil which was in the carbonic acid box ; neither it nor the fila- 



