Preparation of water free from carbonic acid

Preparation of Water free from Carbonic Acid.— 

Water can be freed from carbonic acid by drawing a current of air, free from carbon dioxide, through the water. The air is purified by passing through a tube containii, first, a layer of calcium chloride, then a layer of soda-lime, and lastly (at end next the water), a layer of cotton-wooL This operation should, of course, be carried out in an atmosphere free from fumes (not in the ordinary laboratory), and the air should preferably be drawn from out-of-doors. 

The water is preserved in a flask (preferably of Jena glass), or in a bottle fitted with a siphon tube passing through a closely fitting rubber stopper, or cork protected by paraffin and the air which enters into the flask, on withdrawing water, should be made to pass through a tube of soda-lime. 

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