Intelligence and Miscellaneous Articles. 317 



Domonte and Menard, the mannite, in becoming nitric mannite, 

 must increase considerably in weight (from 100 to 225). 



It is less dangerous in preparation and manipulation : in fact the 

 preparation is merely accompanied with the disengagement of some 

 vapour of nitric acid. 



Fulminating mannite requires for detonation a violent blow be- 

 tween two hard bodies ; heat gradually applied to it fuses and after- 

 wards decomposes it, but without detonation. In fact it may be 

 placed on paper and touched with a red-hot coal, and fused without 

 detonation ; the paper on which it is put may be burnt, and it is 

 decomposed without detonation. 



Lastly, fulminating mannite is decomposed by the blow of a ham- 

 mer, without, as far as appears, producing nitrous vapours. It 

 seems to be entirely decomposed into carbonic acid, water and azote ; 

 besides which it keeps indefinitely without undergoing decomposi- 

 tion.— -Co?np/e* Rendus, Juillet 19, 1847. 



ON THE EXTRACTION OF SILVER. 

 BY MM. MALAGUTI AND DUROCHER. 



From the numerous researches which the authors have made on 

 a large series of specimens from different parts of Europe, they have 

 inferred the general fact, that all metallic compounds which accom- 

 pany or are found near argentiferous minerals contain more or less 

 silver ; so that they deem it an established fact, that silver is pro- 

 bably one of the most widely-diffused metals in nature. 



The researches of the authors have been made on sulphurets, 

 arseniurets, arsenio-sulphurets, some metallic oxides, and even native 

 metals. This fact being established, the mode in which tl>e silver 

 exists occupied their attention. As the subject appeared a difficult 

 one, it was simplified by inquiring in what state the silver existed 

 in galena, blende and pyrites, and they supposed it could exist only 

 in the native state, as chloride or sulplmret. Experiments appeared 

 to show that in these sulphurets the silver is not in the metallic 

 state ; and experiments still more numerous and decisive seemed 

 also to prove that the silver could not be in the state of chloride ; 

 and on this occasion they remarked a circumstance which has hitherto 

 escaped the observation of chemists : — Tliey found that all metallic 

 sulphurets, properly so called, and even some arseniurets, possess 

 the property of decomposing a certain quantity of chloride or bro- 

 mide of silver. This decomposition is effected more or less slowly 

 when contact is effected merely by water ; but it is produced much 

 more rapidly, and in some cases even instantaneously, when the 

 chloride or bromide of silver is in solution. 



By comparative trials the authors succeeded in determining the 

 decomposing power of a great number of sulphurets and several 

 arseniurets. Thus — 



