1820.] of different inorganic Bodies. 356 



of barytes produced 8-693 grammes of sulphate of baiytes. 

 Hence the salt is composed of 



Arsenic acid 42-94 100-00 



Barytes 57-06 132-88 



These 132-88 parts of barytes contain 13-88.67 parts of oxygen ; 

 which approaches very nearly to the analysis of arseniate of lead. 



A portion of arseniate of barytes, which had not been dried, 

 was digested in caustic ammonia, washed, dried, and exposed to 

 a red heat. One hundred parts of this subsalt decomposed by 

 sulphuric acid furnished 102-4 of sulphate of barytes. Hence 

 the salt is composed of 



Arsenic acid 33-44 lOO'OO 



Barytes 66-56 199-04 



But 132-88 X H = 199-32. Hence it follows, that the acid is 

 combined in this salt with 1-i- times as much salt as in the 

 neutral arseniate. 



Arsenite of Lead. — Arsenious acid was dissolved in caustic 

 ammonia, and to separate all the exdess of ammonia, the satu- 

 rated solution was boiled for some time. It allowed a great deal 

 of ammonia to fly off, and a crystalline deposit of arsenious acid 

 took place. The liquid was left for some days in a temperature 

 under 32'^ to get rid of all the excess of acid, which crystallized 

 in octahedrons containing neither ammonia nor water. Then 10 

 grammes of pulverized and dry nitrate of lead were dissolved in 

 water, and the arsenite of lead was poured into the liquid as long 

 as any precipitate fell. The precipitate, being well washed and 

 dried, was introduced into a glass retort, and fused. It produced 

 a yellowish glassy mass, weighing 12-29 grammes. A small 

 quantity of arsenious acid sublimed during the fusion, as always 

 happens when the arsenites are exposed to heat ; but its weight 

 is included in the 12-29 grammes. To determine whether the 

 whole oxide of lead of the nitrate was contained in the fused 

 mass, I examined the liquid from which the arsenite had been 

 precipitated. It became muddy on the addition of sulphuric 

 acid, as was the case likewise with the water employed to wash 

 the precipitate. The quantity of sulphate of lead thus obtained 

 weighed 0-356 gramme, equivalent to 0-261 of pure oxide of lead, 

 which of course must be subtracted from the 6-731 grammes of 

 oxide of lead contained in the 10 grammes of nitrate of lead. It 

 follows that 6-47 grammes of oxide of lead had produced 12-29 

 grammes of arsenite of lead. Of course the salt is composed of 



Arsenious acid 47-356 100-00 



Oxide of lead 52-644 111-17 



But these 111-17 of oxide of lead contain 7-972 of oxygen. 

 A solution of subacetate of lead was precipitated by arsenite of 



