] 10 CHEMICAL THEORY ILLUSTRATED BY NEW FACTS, 



to be expelled. From my analysis* of sulphuretted hydro- 

 gen it would appear, that, if potassium in forming a com- 

 bination with this substance sets free hidrogen, it will be 

 nearly the same quantity, as it would cause to be evolved 

 from water. And if the analysis of Mr. Proust and Mr. 

 Hatchett of the sulphuret of iron be made a basis of calcu- 

 lation, iron, in attracting sulphur from sulphuretted hidro- 

 gen, will liberate the same proportion of hidrogen as during 

 its solution in ^diluted sulphuric acid; and taking Mr. 

 Dalton's law of proportion, the case will be similar with 

 respect to other metals: and if such reasoning were to be 

 adopted, as that metals are proved to be compounds of 

 hidrogen, because in acting upon different combinations 

 containing hidrogen they produce the evolution of equal 

 proportions of this gas, then it might be proved, that almost 

 any kind of matter is contained in any other. The same 



Composition * The composition may be deduced from the experiments in the 



•t sulphuret- j^j Bakerian lecture, which show, that it contains a volume of hidro- 

 I rogen. ^^^^ equal to its own. If its specific gravity be taken as 35 grains, 

 for 100 cubical inches, then it will consist of 227 of hidrogen, and 

 32 73 of sulphur. When sulphuretted hidrogen is decomposed by 

 common electricity, in very refined experiments, there is a slight; 

 diminution of volume, and the precipitated sulphur has a whitish 

 tint, and probably contains a minute quantity of hidrogen. "When it 

 is decomposed by Voltaic sparks, the sulphur is precipitated in its 

 common form, and there is no change of volume ; in the last case the 

 sulphur is probably ignited at the moment of its production. In some 

 experiments lately made in the laboratory of the Royal Institution, on 

 arseniuretted and phosphuretted hidrogen, it was found, that, when 

 these gasses were decomposed by electricity, there was no change in 

 their volumes ; but neither the arsenic nor the phosphorus seemed to 

 be thrown down in their common states; the phosphorus was dark 

 coloured, and the arsenic appeared as a brown powder: both were 

 probably hydrurets.^ This is confirmed likewise by the action of pot- 

 assium upon arseniuretted and phosphuretted hidrogen : when the 

 metal is in smaller quantity than is sufficient to decompose the whole 

 of the gasses, there is always an expansion of volume; so that 

 arseniuretted and phosphuretted hidrogen contain in equal volumes 

 Xf\ovc hidrogen than sulphuretted hidrogen, probably half as much 

 tnore, or twice as much more. From some expeiirccnts made on the 

 weights of phosphuretted and arseniuretted hidrogen, it would appear, 

 that 100 cubic inches of the first weigh about 10 ijrains, at the mean 

 temperature and pressure, and loo of the second about 15 grains. 



quantity 



