248 
MINUTE DIVISION OF MERCURY. 
bility, when mechanically placed under circumstances favor- 
able to chemical action and combination. 
These considerations, originating in the endeavor to ac- 
count for the separation of mercury from chalk by trituration 
with tenacious extracts, induced me to try a variety of expe- 
riments, in order to satisfy myself as to the actual state of the 
metal in that preparation, and the laws which regulate its re- 
duction to and continuance in a state of minute division. 
A portion of hydrarg. cum creta was tied in a piece of 
leather, and subjected to the force of a powerful press ; on re- 
moving it, a considerable quantity of the metal was found to 
have been separated in the form of globules. 
Another portion was boiled in excess of dilute acetic acid, 
so as to ensure the complete saturation of the chalk. The 
residuum was washed with water, and appeared like a black 
powder moistened into the form of a paste. Some of it, in a 
glass with a little water, was placed by the side of another 
glass containing cinereous oxide in the same fluid. The pre- 
cipitates appeared similar, but on adding muriatic acid to 
both, the oxide was converted into calomel, the other remain- 
ed without any visible alteration. The remainder of the 
black paste was dried upon a filter ; as the evaporation pro- 
ceeded the globules appeared, and when it was perfectly dry, 
almost the whole of it assumed the metallic state, as may be 
seen by the result, which is on the table. The same experi- 
ment was tried without using heat, the precipitate being dried 
in the dark. The result is also on the table, consisting chiefly 
of metallic mercury, with a very small quantity of black 
powder. Some of the precipitate in the latter experiment 
was boiled with dilute acetic acid. Before the ebullition 
commenced, the precipitate rose to the surface, floating in the 
form of minute spherical particles. These alternately rose 
and fell in the liquid, like pith balls electrified under a 
tumbler. When cool, their former specific gravity returned, 
and they fell down like a heavy precipitate. The acetic acid 
in which the above had been boiled was tested, and gave no 
indication of the presence of a mercurial salt. 
