on the Muriatic and Oxy muriatic Acids . af# 
and the contraction of volume in muriatic acid electrified over 
mercury. Now the latter effect of the process can be ex- 
plained on no other principle than the absorption of oxymu- 
riatic acid by the quicksilver. 
When muriatic acid and oxygen gases are electrified toge- 
ther over mercury, a gradual diminution ensues in their bulk,* 
and the mercury becomes tarnished, precisely as by the con- 
tact of oxymuriatic acid. I have lately examined the agency 
of this process on a considerable quantity of the two gases 
confined in a vessel, into which they were admitted after ex- 
hausting it by the air-pump. The phenomena, 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 undecom- 
posed muriatic acid, is deposited in drops upon the inner sur- 
face of the vessel, in the state of liquid muriatic acid. When 
the stop-cock, which confine the gases, is opened under mer- 
cury, a quantity of that metal rushes in, and has its surface 
instantly tarnished. Besides this test of the production of oxy* 
muriatic acid, its presence is rendered unequivocal (after ab- 
sorbing the undecomposed muriatic acid by a few drops of 
water), both by its smell, and by its effect in discharging the 
colour of litmus paper. -f* 
These results, it will be found, may be reconciled with 
* Phil. Trans. 1800, p. 193. 
+ Those who wish to repeat this experiment need not be deterred by the apprehen- 
sion of the labour attending it ; for 3 or 400 discharges, from a Leyden jar of mode- 
rate size, are sufficient to occasion a distinct precipitation of moisture. When a 
mixture of oxygen and muriatic acid gases is even suffered to stand over mercury, a 
gradual contraction of volume takes place; the muriatic acid, if in proper proportion, 
entirely disappears ; and calomel is deposited upon the surface of the glass vessel; 
but, in this case, there is no visible production of moisture. 
MDCCCXII. K k 
