154 French Ndttional Institute. 



M. Gay-Lussac has undertaken a laborious investigation, 

 with a view oF appreciating t/ie actio?} of the fire 7ipon the 

 different sulphates and sulphurets, and in order to determine 

 the circumstances in which the sulphuric acid is found com- 

 pLetehj formed or decomposed. He found that this decom- 

 position is effected in the metallic sulphates, in'which the 

 acid is more tenaciously retained, and that there then pass 

 over sulphurous acid and oxvgen ; but this last phcenomenon 

 does nut take place where the acid is feebly condensed. 



As to the suiphurets,. they always give sulphurous acid at 

 a very high teniperature; but at a low temperature they 

 give more sulphuric acid, as the oxide of their metal has 

 more affinity for it. The earthy sulphates and that of am- 

 monia always admit of their acid being decomposed; but 

 those of the fixed alkalis onlv do so when their acid is in 

 excess. The acid alone is very well decomposed by simple 

 heat. From these inquiries results the analysis of the two 

 acids of sulphur; 100 parts of this combustible take 30*6 1 

 of oxygen before being converted into sulphurotis acid, and 

 85*70 before becoming sulphuric acid. " 



We have also, as one of the above results, an explanation of 

 several complex chemical phsenomena, and particularly those 

 which take place at the manufacture of sulphuric acid by the 

 combustion of sulphur in leaden chambers. Sulphur alone 

 would give sulphurous acid only : but the nitre which we 

 burn with, and the atmospheric air admitted, furnish the su- 

 perabundant oxvgen. Water is a necessary intermedium for 

 uniting the oxygen of the air to sulphurous acid, as M. Four- 

 crov lung ago announced. 



JSI. de Morveau has made some curious experiments upon 

 the time necessary for the inflammation of a given mass of 

 gunpowder, and the 'effects which result from it. Coarse 

 powder intlames more speedily than fine. The ordinary 

 working of a gun requires that the ball should run freely in- 

 to the piece, and the space required for this purpose greatly 

 diminishes the'^trength of the powder. But it is singular 

 that by diminishing this interval of room in a gunpowder 

 proof, and making the ball fit very accurately, a still greater 

 joss takes place; probably becaue the explosion, by momen- 

 tarily compressing the globe in the longitudinal direction, 

 dilated it in the transverse direction; and in this case there 

 was too violent a friction of bronze against bronze. Expe- 

 rience having sb.own that leaden bullets pressed into carbines 

 have not this fault, M. de Morveau tried bullets made cy- 

 lindrical behind, aud furnished with a leaden ring, which he 



found 



