192 



An Account of an Apparatus on a peculiar Construction for performing 

 Electro -magnetic Experiments. By W. H. Pepys, Eaq. F.R.S. 

 Read April 10, 1823. [Phil. Trans. 1823, p. 187.] 



This instrument consists of two plates, each fifty feet long and 

 two wide, one of copper and the other of zinc. They are rolled round 

 a cylinder of wood, and their contact is prevented by the interposi- 

 tion of hair rope and notched sticks. This coil is counterpoised and 

 suspended by a rope and pulleys over a tub of acid, into which it is 

 immersed when required for use. When thus immersed, with its 

 poles connected by a sufficient conductor, it affected magnetic needles 

 at a distance of five feet, and was extremely powerful in conferring 

 magnetism upon steel bars, which acquire a north polarity at the 

 copper, and a south at the zinc plate. The electric intensity of the 

 apparatus is exceedingly feeble. 



On the Condensation of several Gases into Liquids. By Mr. Faraday, 

 Chemical Assistant in the Royal Institution. Communicated by Sir 

 Humphry Davy, Bart. P.R.S. Read April 10, 1823. [Phil. 

 Trans. 1823, p. 189.] 



The gases which the author has succeeded in condensing into the 

 liquid form, are, the sulphurous acid, sulphuretted hydrogen, carbo- 

 nic acid, euchlorine, nitrous oxide, cyanogen, ammonia, muriatic acid, 

 and chlorine. The process by which they were condensed, consisted 

 in liberating them from certain of their compounds in small glass 

 tubes, hermetically sealed and bent, so that when required, the end 

 might answer the purpose of a receiver, and be occasionally immersed 

 in ice or freezing mixtures. They generally appear as exceedingly 

 limpid, colourless, and mobile fluids, and assume the gaseous form 

 with various degrees of rapidity and violence upon the removal of 

 that pressure by which they had been previously restrained. 



In this paper Mr. Faraday details the particular method to which 

 he resorted for obtaining each of these liquid bodies, and describes 

 such of their characters as his experiments have hitherto enabled him 

 to determine. 



Liquid sulphurous acid appears to exert a pressure of about 2 

 atmospheres, at 45. The pressure of the vapour of sulphuretted 

 hydrogen was equal to about 13 atmospheres, at 32; that of car- 

 bonic acid to 40 atmospheres, at 45 ; of nitrous oxide 48 atmo- 

 spheres, at 50 ; of cyanogen between 3 and 4 atmospheres, at 45 ; 

 of muriatic acid 28 atmospheres, at 32. 



The author's attempts to obtain hydrogen, oxygen, fluoric, fluo- 

 silicic, and phosphuretted hydrogen gases in the form of liquids, have 

 hitherto been without success. 



