144- Proceedings of Learned Societies. 



" It may, perhaps, be alleged as an objection to this view, 

 that travellers who have crossed the great sandy deserts of the 

 interior of Africa, for the most part describe the contrast 

 between the almost insupportable heat of the day, and the 

 refrigeration of the atmosphere that takes place after the setting 

 of the sun, and which can only be due to the intensity of radia- 

 tion at this period of the evening. It might, I think, be replied 

 to this objection by remarking that in these immense deserts, 

 most often situated at a great distance from the sea, the nearly 

 total absence of water causes the atmosphere to retain a condi- 

 tion of nearly absolute dryness. We admit that the quantity 

 of water which the atmosphere can retain, in the state of elastic 

 vapour, depends upon its temperature ; but it is, nevertheless, 

 necessary that the water should exist, and when there is none, 

 the atmosphere, however high its temperature, is necessarily 

 deprived of that aqueous vapour which is able to intercept the 

 terrestrial radiation with so much power. Besides, there can 

 be no reason why nocturnal radiation should not reach its 

 maximum effect under circumstances which are otherwise 

 entirely favourable to its development, and produce a striking 

 contrast of temperature as soon as the sun has disappeared 

 from the horizon." 



PKOCEEDINGS OF LEAKNED SOCIETIES. 



BY W. B. TEGETMEIEE. 



CHEMICAL SOCIETY.— June IStJt. 



A Cuuious Case of Electrolytic Action. — Among the papers 

 read at the last meeting of the Chemical Society before the vacation 

 was a short note by Mr. Abel, chemist to the War Department, on 

 a singular appearance occasionally shown by Armstrong shot which 

 have been stored some time. It must be premised that there are 

 two modes of completing these shot : in one the iron shot has 

 grooves upon its surface, which help to keep the lead covering 

 which is cast over the iron body in its place; in the other mode 

 the iron shot is firs! "galvanized," i. 0., dipped into a bath of melted 

 zinc, and then into a second bath containing cither an alloy of lead 

 and tin, or lead with a small ] in (portion of antimony. Shot finished 

 as last described, exhibit the peculiar appearance examined by Mr. 

 Abel. One or more blisters are formed, often of considerable size, 

 sometimes one or two inches in diameter, and a quarter of an inch 

 in height. On being opened under water it is found that these 

 blisters contain pure hydrogen gas, existing under a pressure of 

 ten atmospheres. This hydrogen evidently owes its origin to the 



