3? 2 Miscellanies. 



To determine whether azote is the active principle, the author 



brought into contact with a common acid solution of gold, the gas- 

 eous oxide of azote, and the reduction of the metal was soon manifest. 

 One portion was deposited on the sides of the vessel, and another 

 covered the bubbles of air as they arose, with a metallic pellicle, and 

 in a short time the gold was separated from the liquid. 



The reduction is also effected by nitric acid. If a tube containing 

 some solution of gold be placed in a bottle over fuming nitrous acid, 

 the reduction takes place. But the gaseous oxide of azote and ni- 

 trous acid do not effect the reduction of palladium, nor probably of 

 any other metal. 



Evaporation appears to be a necessary condition in the reduction 

 of silver and platina, for the azote is presented only in proportion as 

 the acids of the salts are dissipated by evaporation. 



In experiments upon the reducing power of azote, the light must of 

 course be excluded. 



The compound of oxide of azote and potash, which is always ob- 

 tained by heating saltpetre to redness, after carefully separating all 

 the other products from it, reduces the solution of gold promptly and 

 completely, but it does not reduce the other metals. — Bib. Univ. 



April, 1830. 



>/ 



In attempting to 



ascertain the kind or quality of zinc most suitable for voltaic instru- 

 ments, Professor De La Rive was forcibly struck with the great dif- 

 " ference which he found in the action of dilute sulphuric acid upon 

 pure zinc, obtained by distillation, and the ordinary zinc of commerce. 

 With the former, the action is very slow and feeble, and but little hy- 

 drogen gas can be obtained, — with the latter, which is always hetero- 

 geneous, the action, as is well known, is very great, and the evo- 

 lution of gas rapid and abundant. The great difference, in these cases 

 both with respect to the quality of the zinc, and the dilution of the 

 acid, he justly conceived had not been sufficiently investigated. 



To determine with precision the difference in the activity of these 

 materials, in different states of purity and mixture, he employed a 

 ground stopped flask or vial, of one ounce capacity, to the bottom of 

 which was attached a lateral tube, which, being bent upwards, was 

 graduated into equal parts, and was large enough to receive all the 

 fluid contained in the flask. A cylinder of zinc being attached by 

 wax to the glass stopper, and so adjusted as to be easily pushed into 

 the acid, the quantity of gas disengaged in a given time, rising to the 



with 



great 



