Miscellan ies. 199 



6. Russia Diamond Mines. — When in the year 1S2G, Professor 

 Engelhardt undertook a scientific journey into the Uralian Moun- 

 tains, he remarked that the sands in the neighborhood of Koushra, 

 and those of the platina mines at Nigny-Toura, strikingly resembled 

 the Brazilian sands in which diamonds are found. Baron Humboldt, 

 during his late residence in the same country, confirmed this resem- 

 blance; and examinations having been made according to his advice, 

 a young countryman who was employed in washing the auriferous 

 sand, on the grounds of the Countess Polier, discovered a diamond 

 on the 20th of June last, which was in nothing inferior to those of 

 Brazil ; soon after, many others were found superior in weight to the 

 first. Thus Russia has added this source of riches to those which 

 of late years it has obtained in the form of gold and platina mines 

 from the Ural chain of mountains. — Revue Encyc. xlv. 460. 



7. Extract of letters of Dr. Comstock to the Editor on the cause 

 of the premature explosion of gun powder, particularly in blasting 

 of rocks; dated Lebanon, Con., Nov. 9, 1829. — On the first day 

 of June, 1825, my professional attendance upon two men at Bozrah 

 Ville, was requested in consequence of the premature ignition of 

 the charge in a rock which they were preparing to blast, both of 

 whom were severely injured, and one of whom, a Mr. Swift, re- 

 mains nearly blind. 



Upon a minute enquiry respecting the origin of the fire, I became 

 convinced that it could not have arisen from any collision between 

 metal and stone, as the w r ire was copper. At the instant of the ex- 

 plosion one of these men was in the act of striking down the cover- 

 ing of the charge with a sledge weighing fifteen pounds, and I am 

 disposed to think that the fire in this, and perhaps in other cases of 

 premature ignition, originated from the compression of the air in the 

 hole of the rock. Any one who has seen the little instrument called a 

 fire pump, and who has seen fire obtained by a stroke of the hand upon 

 its piston, cannot be a moment at a loss to account for the origin of 

 the fire in this and in similar instances, depending upon the conden- 

 sation of atmospheric arr, and the friction of the piston evolving heat 

 or electricity, or probably both. It appears to me scarcely to admit 

 of doubt, that this is the true cause, and this opinion is fortified by the 

 fact that an explosion of powder both in muskets and in artillery 

 sometimes happens whilst the charge is ramming down, and the origin 

 of the fire has often been considered as unaccountable. But if the 



