1520.] of different inorganic Bodies. 359 



some drops of a liquid which distiited over, and which was the 

 anhydrous combination of murial't; and arsenious acids. Then 

 a subhmate rose of a deep red rjlour, which lined the inside of 

 the tube ; and lastly, an amali: an of arsenic covered the inside 

 of the red sublimate. I seuurated them, and mixed the non- 

 metalhc mass with a new do^e of metallic arsenic, and sublimed 

 it anew by a very gentle lieat. The sublimate was at first trans- 

 parent, and of a fine red, inchnino- a little to yellow ; but as it 

 became thicker, it acquired a darker shade, and lost its transpa- 

 rency. The metallic arsenic remained in the phial. The subli- 

 mate was easily detached from the glass. Its colour was brown, 

 its fracture earthy, without any marks of crystallization, and its 

 powder yellow. It was insoluble both in water and muriatic 

 acid. Copper rubbed with the powder moistened with muriatic 

 acid was not attached. PJixed with iron filings, and exposed to 

 heat, it gave out arsenic, which subluned in crystals. The fixed 

 caustic alkalies decomposed this mass almost instantly ; and so 

 did ammonia after a short interval. Muriate and arsenite of the 

 alkali were found in the liquid, and there remained an amalgam 

 of arsenic. Hence the sublimate was a double salt, having for 

 its bases protoxide of mercury and oxide of arsenic, which, as 

 happens with the oxides of sulphur and of phosphorus, is decom- 

 posed the instant it is disengaged, producing arsenious acid, and 

 allowing a part of its radical to be reduced to the metallic state. 

 In this case, the metallic arsenic had likewise reduced the 

 mercury, so that its quantity was so much the more reduced. 



I have no doubt that it is possible to obtain the combination of 

 muriatic acid with oxide of arsenic Avithout the presence of proto- 

 muriate of mercury ; but I have not made the necessaiy experi- 

 ments either to determine this point, or to find the quantity of 

 oxygen with which the arsenic is combined to constitute the 

 oxide ; so that I cannot say whether the oxide of the double salt 

 of which I have just given the description, is the same as the 

 black oxide formed by exposing metallic arsenic to the air. 



Sulp/iiaets of Arsenic. — Klaproth and Laugier made experi- 

 ments on the native sulphurets of this metal, and each of them 

 obtained the same results. M. Haiiy having had reason to 

 suspect that these two sulphurets have the same primitive crys- 

 talline form, he concluded that their chemical composition must 

 also be the same, though the external characters were altered by 

 some accidental mixture. M. Laugier, while occupied with 

 these researches, found that the two native sulpWurets, when 

 heated in a phial, gave a sublimate of arsenious acid, which was 

 more abundant from the red sulphuret than the yellow. The 

 fused mass thus deprived of arsenious acid had always the same 

 composition. He found in the red sulphuret 43-67 sulphur in 

 143-(J7 of sulphuret, in the yellow sulpliuret 61-()6 sulphur in 

 lfcil-66 of sulphuret, and in the fused sulphuret, from which the 

 arsenious acid had been driven, from 71-3 to 71-89 sulphur in 



