Quicksilver is a substance of paramount value to science. Its great density and its regular rate of expansion and contrac tion by increase and diminution of tem perature, give it the preference over all liquids for filling barometric and thermo metric tubes. In chemistry it furnishes the only means of collecting and manipu lating, in the pneumatic trough, such gaseous bodies as arc condensable over water. To its aid, in this respect, the modern advancement of chemical discov ery is pre-eminently due.
This metal alloyed with tin-foil forms the reflecting surface of looking-glasses, and by its ready solution of gold or silver, and subsequent dissipation by a moder ate heat, it becomes the great, instrument of the arts of gilding and silvering copper and brass. The same property makes it so available in extracting these precious metals from their ores. The anatomist applies it elegantly to distend and display the minuter vessels of the lymphatic sys tem, and secretory systems, by injecting it with a syringe through all their convo lutions. It is the basis of many very
Powerful medicines.
Mercury dissolves a11 the metals except iron, forming amalgams with them. With arsenic and antimony by heat.
Mercury may be cleansed by forcing it through chamois leather, hazel wood, or a cone of fine paper. Sometimes it is shaken in a bottle with powdered loaf sugar, and then passed through a paper funnel. If mixed with other metals, it should be distilled.
The nitrate of mercury is employed for the ma. etage of rabbit and hare-skins, that is, for communicating to the fur of these and other quadrupeds the faculty of felting, which they do not naturally possess. With this view the solution of that salt is applied to them lightly in one direction with a sponge. A compound amalgam of zinc and tin is probably the best exciter which can be applied to the cushions of electrical machines.
The only mercurial compounds which are extensively used in the arts, are facti tious cinnabar or vermillion, and corro sive sublimate.