360 On the Purification of Mercury. 
Neither do J pretend that the method of which I speak is 
positively new ; perhaps it may be known, and probably other 
artificers for private interest have kept it secret*. But as I 
have not seen it noticed in any book, I have thought it proper 
to describe briefly the experiments which I have made on this 
subject, from which at least it may be more generally known that 
by means of some acids, the mercury of commerce may be puri- 
fied sufficiently to serve in a great number of experiments not 
enly in general physics, but also in chemistry. 
I put in different vessels the quantity of three pounds in each; 
over one | poured a sufficient portion of strong vinegar, and over 
the other diluted sulphuric acid. By agitating and often shaking 
the vessels the mercury divided into sniall globules, and. pre- 
sented more points of contact to the acids; and I observed that 
they became turbid, and that with reagents they indicated having 
metallic matter in solution. Continuing the purification and 
renewing the quantity of acids, on the fourth day I separated 
the mercury from them, and aiter washing, drying, and passing 
it through « hole made with a pin in the ibottens of a funnel of 
writing- -paper, I placed it in different vessels. ‘The mercury 
purified in this manner had a bright surface even after the space 
of several days. 
This result encouraged me to try directly the same process 
on the adulterated mercury of commerce ; and I made the ex- 
periment with success. I purified a great deal at different times, 
preferring however the diluted sulphuric to the acetic acid, be- 
cause it may be used even still stronger, and it has a more power- 
ful action on the extraneous metals. Such an operation, in which 
the sulphuric acid may be renewed a greater or lesser number of 
times, succeeds in a longer or shorter period; but it is not con- 
sidered as terminated until the mercury divides, and continues for 
a considerable tinre in very minute globules, and without altering 
the acid, which must retain its transparency, and evince no trace 
of any metallic substance by reagents. In March 18138 I di- 
stilled in an earthen retort about seventeen pounds of mercury, 
which [ used for various experiments, and which contained much 
lead and tin. Although it had abandoned an abundant share of 
these metals, yet by the pellicle on its surface it was evident that 
it still contained much amalgam, an effect to which the still had 
* In 1806, my friend and colleague Sign. Savi, then Professor of Experi- 
mental Philosophy (now Professor of Botany, and the unassuming author of 
several valuable tracts on the indigenous plants and forest and other trees 
of Tuscany), observed that a Milanese barometer-maker, purified his mer. 
cury by means of a fluid, the nature of which he studiously concealed. 
+ My assistant in the laboratory annually constructs mary barometers 
and thermometers, and he finds that mercury purified in this manner is of 
great advantage. 
perhaps 
