4-32 



to the quantity which has been stated, nothing further is gained by 

 continuation of the process. 



When mercury is not present during the electrization, then a dif- 

 ferent result is obtained. The quantity of hydrogen is estimated by 

 the author not to exceed one seventieth part of the gas employed. 

 The gas does not appear to be changed in bulk ; but a part of it is 

 converted into oxymuriatic acid gas. When this gas amounts to a 

 certain proportion of the mixture, the effect of the electricity will 

 then be to re-unite it to the hydrogen, and form muriatic acid gas 

 rather than to decompose it. 



But when mercury is present, it removes the oxymuriatic acid as 

 fast as it is formed ; and then a larger proportion of hydrogen is 

 evolved, till every nascent portion of oxymuriatic acid gas is so sur- 

 rounded by hydrogen that it cannot attain to a state of actual extri- 

 cation. 



In support of this explanation, Dr. Henry mixed thirty measures 

 of hydrogen with 400 of muriatic acid gas ; and when this mixture 

 was electrified over mercury, no effect was produced ; the quantity 

 of hydrogen was not increased ; and it was evident that no oxymu- 

 riatic gas was evolved, as the surface of the mercury remained with- 

 out the slightest tarnish. 



When, on the contrary, the muriatic acid gas was mixed with 

 oxygen, and electrified over mercury, then a diminution of bulk en- 

 sued, and the surface of the mercury became tarnished, as by the 

 contact of oxymuriatic gas ; and water was formed in drops, and de- 

 posited on the inner surface of the vessel, combined with a portion 

 of the muriatic acid. 



These results, says Dr. Henry, may be explained either according 

 to the commonly received theory, or according to that adopted by 

 Mr. Davy. 



According to one view the oxygen unites to the real acid of the 

 muriatic gas, and forms oxymuriatic gas, which then deposits water 

 that had been previously held in solution. According to the other, 

 the oxygen unites with the hydrogen, and forms water, while the 

 oxymuriatic base is now disengaged as a simple body. 



The author, at present, is not acquainted with any ground for 

 giving a preference to one above the other of these two modes of ex- 

 planation ; but he imagines that something would probably be gained 

 by a precise determination of the proportions in which the gases sa- 

 turate each other. He has not, however, been able to satisfy himself 

 on this point ; and he conceives that the condensation of a portion 

 of the muriatic acid gas by the water that is formed during the pro- 

 cess, is an almost insuperable impediment to any precise determina- 

 tion of these proportions. 



