Royal Society. 125 



and must exceed 150 tons of solid bicarbonate of ammonia 

 per annum : and if, as is extremely probable, other animals 

 also exhale this substance, the atmosphere must not only 

 always contain enough of this agent for the purposes of vege- 

 tation, but, by a reciprocal action, the mutual increase of ve- 

 getables and animals would only tend to render the air better 

 adapted for the due development of both. The existence of 

 ammonia in the breath may easily be demonstrated, by re- 

 spiring air which has passed through diluted sulphuric acid, 

 and then expiring it through a tube surrounded by water at 

 32° F., to the further end of which a vessel is attached to re- 

 ceive the fluid which condenses. On acidulating this fluid 

 with one or two drops of pure muriatic acid and evaporating 

 to dryness on a water-bath, a residue will be obtained, which, 

 when dissolved in five or six drops of water and introduced 

 into a small test-tube^ will give off" ammonia on the addition 

 of two or three drops of a strong solution of potash, as evi- 

 denced by its action on turmeric paper and muriatic acid, or 

 by its peculiar smell. The respiratory process should be con- 

 tinued for an hour or two. 



It would be interesting to know whether any difference is 

 observable in the amount of ammonia exhaled from the lungs 

 of individuals suffering from disease of the kidney, diabetes, &c. 

 I am. Gentlemen, 



Your most obedient Servant, 

 Byker Bar, Newcastle- on-Tyne, Lewis THOMPSON. 



Jan. 13, 1847. 



XXVI. Proceedings of Learned Societies. 



ROYAL SOCIETY. 

 [Continued from p. 59.] 

 Jan. 7, "/^UELQUES Recherches sur I'Arc Voltaique; et sur 

 184'7. ^'^ I'influence qu'exerce le Magnetisnie, soit sur cet Arc, 

 soil sur les Corps qui transmettent les Courants Electriques Dis- 

 continus." By M. Auguste De la Rive, Foreign Member of the 

 Royal Society, Professor in the Academy of Geneva, Corresponding 

 Member of tlie Academy of Sciences of Paris, &c. 



In tlie first section of this memoir tiie author gives a detailed de- 

 scription of tiif; piieiiomona exhibitcci by tiie luminous voltaic arc 

 produced eitlicr in a vacuum or in atmospheric air, or in hydrogen 

 gas, Ijy employing electrodes of different kinds of conducting sub- 

 stances, in the form cither of points or of plates. lie examines mi- 

 nutely the transfer of particles which takes place from one pole to 

 the other under these various circumstances, and the differences 

 wliidi occur when the currents arc reversed. He observed that 

 when a positive metallic point is presented to a negative ])late, par- 

 ticles of the former are transported by the voltaic arc, and deposited 



