154 Intelligence and Miscellaneous Articles. 



therefore volatilizes much more readily than was supposed : it incrusted 

 the surfaces of the apparatus employed ; the same happens to the 

 silver in roasting galenas ; this fact explains an important metallurgic 

 fact, which is, that notwithstanding the j)recautions taken to collect 

 pulverulent cadmium in the condensation chambers, there is always 

 a considerable loss of silver which is carried up, and fixed on the sur- 

 face of the apparatus, that it cannot be detached ; this was shown 

 to be the case by experiments. 



Silver is unequally diffused in the various metallic compounds : 

 thus oxides and saline combinations are always poorer thansulphurets, 

 and among the latter, the compounds with a radical of iron are gene- 

 rally less rich in silver than those of lead, copper and zinc. These 

 remarks on the unequal distribution of silver in natural substances, 

 are moreover confirmed by what passes in the operations in the dry 

 way, whether performed in the laboratory or metallurgic establish- 

 ments. 



The universal diffusion of silver in the mineral kingdom induces 

 the belief that other metals are perhaps as widely disseminated in 

 nature ; this is already known to be the case with iron. With this 

 view the authors examined crystalline minerals possessing all the 

 characters of purity. Twelve specimens of galena, besides silver, 

 contained very sensible quantities of iron, coi:)per and zinc. 



In order to ascertain the state in which silver is associated in small 

 quantity in various metallic minerals, and especially in sulphurets, 

 sulphoarseniurets, and sulphoantimoniurets, such reagents were first 

 employed as were supposed capable of acting upon metallic silver, 

 and not upon its sulphuret, especially when it is combined with other 

 metallic sulphurets. Neither liquid chlorine, bichloride of copper, 

 nor persulphate of iron gave very positive results : mercury yielded 

 more precise indications : of thirty-eight specimens operated upon, 

 and of which some were considerably rich, eleven only yielded to 

 mercury a part of their silver. I'he comparison of results deduced 

 from experiments made under similar conditions upon substances into 

 which metallic silver or its sulphuret had been in various ways intro- 

 duced, led to the conclusion that the silver, probably, does not exist 

 in the same state in all sulphurets, containing small quantities of it, 

 but that it is most frequently combined in the state of sulphuret with 

 the substance which it accompanies. 



The authors have completed their preceding experiments, demon- 

 strating that metallic sulphurets cannot contain silver in the state of 

 chloride or bromide ; and they have noticed some remarkable reactions 

 occurring between chlorides and sulphurets. The authors divide 

 these into three groups : — Ist, bimolecular sulphurets, such as those 

 of zinc, cadmium, lead, &c. ; 2ndly, sulphurets possessing several 

 molecules of sulphur, and capable of parting with some of it, bisul- 

 phuret of tin for example; 3rdly, suli)huretsnot saturated with sulphur 

 and susceptible of combining with it, such as the protosulphuret of 

 copper. 



The first react upon the chloride of silver by double decomposition ; 

 the second undergo partial reduction, becoming protosulphuret; the 



