342 On the Muriatic and Oxymurialic Acids. 



its amount, which, it formerly appeared to me*, could 

 only be accounted for by the complete destruction of the 

 water contained in the gas, may now be equally well ex- 

 plained on the principle which I have just pointed out. 

 The tact, also, that no appreciable change of bulk is pro- 

 duced by the electrization of the muriatic acid, when the 

 presence of mercury is excluded, is perhaps favourable tii 

 the new theory. For, since equal measures of hydrogen and 

 oxymuriatic acids afford muriatic acid without any conden- 

 sation of volume, no alteration of bulk should result from 

 the disunion of those elements ; and the products should 

 be equal measures of the satne gases. The proportions 

 which 1 obtained (100 to HO) did not, it must be acknow- 

 ledged, exactly correspond with the theory ; but the dif- 

 ference was not greater than might naturally be expected 

 from the circumstances of the experiment. That equal 

 measures of hydrogen and oxymuriatic acid are reially 

 evolved, appears to me to be proved by the agreement, 

 which I have in several experiments remarked, between the 

 hydroaen gas obtained, and the contraction of volume in 

 muriaUc acid electrified over mercury. Now the latter 

 effect of the process can be explained on no othe'^ orinciple 

 than the absorption of oxymuriatic acid by the quicksilver. 

 When muriatic acid and oxyg'^n gases are electrified to- 

 gether over niercury, a gradual diminution ensues in their 

 bulk t, and tiie mercurv becomes tarnished, precisely as by 

 the contact of oxymuriatic acid. 1 have lately examined 

 the ao-ency of this process on a considerable quantity of 

 the two gases confined in a vessel, into which they were 

 admitted after exhausting it by the air-pump. 'I'he phse- 

 riomena, which in this way of making the experiment are 

 extremely decisive and interesting, are the production of 

 water and of oxymuriatic acid. The former, combining 

 with a portion of the undecomposed muriatic acid, is de- 

 posited in drops upon the inner surface of the vessel, in the 

 State of liquid muriatic acid. When the stop-cock, which 

 confines the gases, is opened under mercury, a quantity of 

 that metal rushes in, and has its surface instantly tarnished. 

 Besides this test of the production of oxymuriatic acid, its 

 presence is rendered unequivocal (after absorbing the un- 

 decomposed muriatic aciil by a few drops of water), both 

 by its smell, and by its effect in discharging the colour of 

 litmus paper t- These 



* Phil. Trans. 1800, p. 'JOO.— Phil. Mag. vol. vii. p. 217. \ Phil. 



Trans. 1800, p. 193.— Phil. Mag. vol. vii. p. 215. 



i Those who wish to repeat this experiment need not be deterred by 

 the apprehension of the labour aitcndiug it ; for 3 or 400 di!>cbarge>, from 



a Leyden 



