Bibliography. 201 



experimenter, and intent on meteorological inquiries. Furnished with 

 every variety of instruments that could contribute to insure accuracy, 

 the observers stationed themselves, the one at the summit of the moun- 

 tain, and the other at its base, the difference in altitude being six thou- 

 sand eight hundred and forty four feet, and therefore comprising nearly 

 one fourth of the whole weight of the atmosphere. Their observations 

 were prosecuted for a number of days during the month of September, 

 under favorable circumstances, and the following conclusions, among 

 others, were fully established : 



That, on the hypothesis of uniform opacity, a standard atmosphere 

 of 29*922 inches, having a mean dampness or ratio to saturation rep- 

 resented by *56 nearly, would transmit 68£ per cent., or stop 31£ per 

 cent, of the incident heating rays ; 



That the absorption of the solar rays by the strata of air to which 

 we have immediate access, is considerable in amount, even for mode- 

 rate thicknesses ; 



That the tendency to absorption through increasing thicknesses of 

 air, is a diminishing one ; and that the absorption almost certainly 

 reaches a limit beyond which no further loss will take place by an in- 

 creased thickness of similar atmospheric ingredients ; and that the 

 physical cause of this law of absorption appears to be the non-homo- 

 geneity of the incident rays of heat. 



12. Memoirs of the Chemical Society of London for 1841, '42, and 

 '43. Vol. I. R. & J. E. Taylor, London, 1843. pp. 258, 8vo. With 

 the Proceedings of the Society for the same period, pp. 64, 8vo. 



This valuable volume is the first fruits of the Chemical Society estab- 

 lished in London in 1841. It contains forty two articles from twenty 

 nine different authors, among whom are many of the most eminent 

 chemists in England, and several names of high renown on the conti- 

 nent ; of the former we may mention Drs. Ure, Graham, Johnston, 

 Gregory, Play fair, &c. &c, and from the continent, Liebig, Bunsen, 

 Stenhouse, Will, &c &c. 



Dr. Playfair's article on the milk of the cow, is a very interesting 

 one, and valuable in a practical point of view, as indicating the best 

 modes of feeding cows, and showing the changes in composition of the 

 milk of a cow according to its exercise and food. Dr. Gregory gives 

 a new method for obtaining pure silver from the chloride, by treating 

 the latter, while still moist, with a strong solution of caustic potash, 

 (sp. gr.=r25,) enough of which is added to cover the chloride half 

 an inch in depth, and then boiled; the chloride is thus all speedily con- 

 verted into brown oxide of silver, which is washed with hot water to re- 

 move chloride of potassium, and is then either kept as oxide of silver 



Vol. xlvi, No. 1.— Oct.-Dec. 1843. 26 



