

1814.] Chemical Proportions. 18 



made out ; but there is still an obscurity hanging over the. chlorides 

 of the metals. There can be no doubt that muriatic acid has the 

 property of combining with metallic oxides, and forming salts ; for 

 if you dissolve iron or zinc in muriatic acid, you obtain just the 

 same bulk of hydrogen gas as if you dissolve the same weight of 

 these metals in sulphuric acid. Now as the hydrogen in the last 

 case comes from the decomposition of water, I do not see how we 

 can hesitate to ascribe it in the first case to a similar decomposition; 

 and then all the rest follows of course : but on the other hand, 

 when sodium and chlorine combine directly, we obtain a substance 

 possessing exactly the properties of common salt. The same ob- 

 servation applies to all the metals. Hence I do not see how any 

 other explanation of these combinations can be given than that 

 which Davy has offered ; though I must own that 1 am far from 

 being satisfied with it, as it supposes the decomposition and compo- 

 sition of water with a degree of facility much greater than has been 

 hitherto observed. 



I shall now give a table of the composition of such of the 

 chlorides as have been made out with tolerable exactness. Indeed, 

 from the great insolubility of chloride of silver, I conceive that 

 these analyses are in general more accurate than those of any other 

 class of bodies, except the sulphates. 



Number of Weight of an 



atoms. integrant parii' le. 



251 Chlorine 4- 19s » 



252 Chloride of oxygen {eiichlorine) 1 ch + \ o .... £ "498 u 



253 Muriatic acid' 1 ch + 2 h .... 4'7<J2 c 



254 Chloride of sulphur 1 ch + 1 s 6-498 d 



a This number results from the supposition that the euchlorine 

 gas of Davy is composed of one atom of chlorine and one of 

 oxygen, and that the specific gravity of chlorine gas is 2*483, which 

 1 find to be nearly the truth. Sir H.Davy's number is 4*466, 

 which does not differ much from mine. Dr. Wollaston's number 

 is 4-410. The theory of volumes would had us to adopt half my 

 number as the weight of an atom of chlorine. It is impossible to 

 say which hypothesis is correct : but the number I have chosen 

 exhibits the simplest view of the composition of the chlorides. 



b This gas is composed of two volumes of chlorine gas and one 

 volume of oxygen gas. 



e This supposes muriatic acid to be composed of equal volumes 

 of chlorine and hydrogen, which agrees with experiment. 



d According to Davy, 10 grains of sulphur absorb 30 cubical 

 inches of chlorine. Now 30 cubic inches of this gas weigh 2'2'7\ i J 

 grains. Now I : 227 19 :: 2 : 227 19 X 2. And 4-5438 differs 

 but little fiorn the weight of an atom of chlorine. 



