342 Mr. Davy's Electrochemical Researches on 
of plate glass, or in some cases in tubes of common glass. 
These tubes were bent in the middle, and the extremities 
were enlarged, and rendered globular by blowing, so as to 
serve the purposes of a retort and receiver. 
The tube after the amalgam had been introduced, was 
filled with naphtha, which was afterwards expelled by boiling, 
through a small orifice in the end corresponding to the 
receiver, which was hermetically sealed when the tube con- 
tained nothing but the vapour of naphtha, and the amalgam. 
I found immediately that the mercury rose pure by distilla- 
tion from the amalgam, and it was very easy to separate a 
part of it ; but to obtain a complete decomposition was very 
difficult. 
For this nearly a red heat was required, and at a red heat 
the bases of the earths instantly acted upon the glass, and 
became oxygenated. When the tube was large in proportion 
to the quantity of amalgam, the vapour of the naphtha fur- 
nished oxygene sufficient to destroy part of the bases : and 
when a small tube was employed, it was difficult to heat the 
part used as a retort sufficient to drive off the whole of the 
mercury from the basis, without raising too highly the tem- 
perature of the part serving for the receiver, so as to burst 
the tube.* 
In consequence of these difficulties, in a multitude of trials, 
I obtained only a very few successful results, and in no case 
could I be absolutely certain that there was not a minute por- 
tion of mercury still in combination with the metals of the 
earths. 
* When the quantity of the amalgam was about fifty or sixty grains, I found that 
the tube could not be conveniently less than one-sixth of an inch in diameter, and of 
the capacity of about half a cubic inch. 
