C 40 3 



1. Qxygene forms about one-fifth of the air of our 

 atmosphere. It is an elastic fluid, at all known tem- 

 peratures. Its specific gravity is to that of air as 10967 

 to 10000. It supports combustion with much more 

 vividness than common air; so that if a small steel 

 wire, or a watch spring, having a bit of inflamed wood 

 attached to it, be introduced into a bottle filled with 

 the gas, it burns with great splendour. It is respirable. 

 It is very slightly soluble in water. The number re- 

 presenting the proportion in which it combines is 1 5. 

 It may be made by heating a mixture of the mineral 

 called manganese, and sulphuric acid together, in a 

 proper vessel, or by heating strongly red lead, or red 

 precipitate of mercury. 



2. Chlorine, or oxymuriatic gas, is like oxygene, a 

 permanent elastic fluid. Its colour is yellowish green, 

 its smell is very disagreeable ; it is not respirable ; it 

 supports the combustion of all the common inflam- 

 mable bodies except charcoal ; its specific gravity 

 is to that of air as 24677 to 1OOOO ; it is soluble 

 in about half its volume of water, and its solution in 

 water destroys vegetable colours. Many of the 

 metals (such as arsenic or copper) take fire spon- 

 taneously when introduced into a jar or bottle filled 

 with the gas. Chlorine may be procured by heating 

 together a mixture of spirits of salt or muriatic acid, 

 and manganese. The number representing the pro- 

 portion in which this gas enters into combination 

 is 67. 



3. Hydrogene, or inflammable air, is the lightest 

 known substance ; its specific gravity is to that of air 



