If these crystals are hermetically sealed up in a glass tube, they will, on melting, exert such a pressure as to liquefy a portion of the gas, which is distinctly seen as a yellow fluid, not miscible with the water which is present.

Chlorine is one of the heaviest of the gases, its density being 2.47, and 100 cubic inches weighing 76.5 grains.
Chlorine Water .-- This combination, which is used in conducting M.
Neipce's process, can be readily prepared by conducting the gas into a bottle containing distilled water.

One part water dissolves two parts of chlorine.
Chlorides .-- The metallic chlorides are nearly all soluble in water; that of silver and protochloride of mercury being the only exceptions.
A metallic chloride, treated with oil of vitriol, disengages chlorohydric acid.

Heated with a mixture of peroxide of manganese and sulphuric acid, chlorine is given off, which is easily recognized by its odor and other physical properties.
The chlorides dissolve in water; give with nitrate of silver, a white precipitate, even in highly diluted solutions, becoming violet colored and finally black when exposed to the light.

The rapidity of the change of color is proportioned to the intensity of the light.