Proceedings of Learned Societies. 



459 



Gunpowder. 

 100 lbs. occupy 1"8 cubic feet 

 55'5 lbs. occupy 1 cubic foot. 



Gun Cotton. 

 100 lbs. occupy 4 cubic feet. 

 25 lbs. occupy 1 cubic foot. 



Products of Explosion. 



10 lbs. yield on explosion, 

 68 lbs. of solids, 

 32 lbs. of gases, 



100 lbs. yields on explosion, 

 25 lbs. of steam, 

 75 lbs. of permanent gases. 



At a lecture delivered at the United Service Institution, Profes- 

 sor Abel combated some of the conclusions arrived at by Mr. Scott 

 Russell, particularly that which attributes the great recoil produced 

 by gurjpowder to the projection of the solid residue remaining after 

 the explosion. Professor Abel contended that some of the materials 

 regarded as solid by Mr. Russell, excited a state of vapour at a red 

 heat, particularly the sulphide of potassium, which forms a consider- 

 able proportion of the residue. It was also shown that the amount 

 of recoil depends greatly on the mechanical aggregation of the ex- 

 plosive body. Loose gun-cotton exploded on one pan of a pair of 

 scales producing no depression, whereas, if plaited into a car- 

 tridge, its effect is well marked. 



In the same manner, the recoil produced on a balance by the 

 explosion of gunpowder is much lessened by previously reducing it 

 to a state of fine powder. From these and other considerations, 

 Mr. Abel regarded the theory advanced by Mr. Russell to accouDt 

 for the greater recoil of gunpowder as unsatisfactory. 



May 19. 



Temperature and Climate op the Moon. — Mr. Nasmyth, who 

 has devoted many years to the diligent observation of Lunar Phe- 

 nomena, communicated the results of his observations to the mem- 

 bers of the Royal Institution, at the Friday evening meeting of this 

 date. 



The bulk or solid contents of the moon, as compared with that 

 of the earth, is as 1 to 49. The surface of the moon, as compared 

 with that of the earth, is as 1 to 16. On the supposition that the 

 moon and the earth were formed at the same period, by the con- 

 densation of nebulous matter, the rapidity of cooling of the moon 

 would be four times as great as that of the earth, in consequence of 

 its greater surface as compared with its solid contents, hence the 

 moon would have become solid long before the earth, and would offer 

 for our contemplation an object of immense antiquity, the surface of 

 which, from the absence of air and water, would, according to Mr. 

 Nasmyth's hypothesis, have undergone no disintegration or change 

 for millions of ages. 



The present condition of the moon's surface, consisting of nume- 

 rous craters of extinct volcanoes, some, twenty-eight miles in dia- 

 meter, is in course of description by Mr. Webb in the Intellectual 

 Observer. Some of these volcanic mountains are 28,000 feet high. 

 These are brightly illuminated on one side by the sun ; and from 

 the absence of diffused daylight, owing to the want of an atmosphere, 



