Page:Experimental researches in chemistry and.djvu/72

1821.] the liberation of carbon, as the per chloride does with the liberation of chlorine, but we have not yet been able to ascertain that point. We have only to offer as an apology for this and other imperfections in the present paper, the smallness of the quantity of this substance that we possessed.

On the Vapour of Mercury at common Temperatures

T has long been admitted, that in the upper part of the barometer and thermometer an atmosphere of mercury exists, even at common temperature, but having a very small degree of tension. The following experiment renders it easy to show this atmosphere even when the air has not, as in the instruments above mentioned, been removed. A small portion of mercury was put through a funnel into a clean dry bottle, capable of holding about six ounces, and formed a stratum at the bottom not one-eighth of an inch in thickness: particular care was taken that none of the mercury should adhere to the upper part of the inside of the bottle. A small piece of leaf-gold was then attached to the under part of the stopper of the bottle, so that when the stopper was put into its place, the leaf-gold was enclosed in the bottle. It was then set aside in a safe place, which happened to be both dark and cool, and left for between six weeks and two months. At the end of that time it was examined, and the leaf-gold was found whitened by a quantity of mercury, though every part of the bottle and mercury remained apparently just as before.

This experiment has been repeated several times, and always with success. The utmost care was taken that mercury should not get to the gold, except by passing through the atmosphere of the bottle. I think therefore it proves, that at common temperatures, and even when the air is present, mercury is always surrounded by an atmosphere of the same substance.

Experiments on the Alloys of Steel, made with a View to its Improvement. By and.

N proposing a series of experiments on the alloys of iron and steel with various other metals, the object in view was twofold: