The Romance of Modern Chemistry

ACIDS AND ALKALIS The more powerful acids have a destructive and cor- rosive action not only on metals, but on many other substances also, notably on organic materials. The most outstanding in this respect is sulphuric acid or oil of vitriol, an innocent enough looking liquid, which, however, is extraordinarily destructive of animal and vegetable tissue, and requires very careful handling. If a drop of it gets on the skin and is not at once washed off’, a very painful wound is produced. Occasional newspaper reports show that there are people who regard vitriol throwing as a proper way of settling old scores, but from what has been said it will be understood that it is a diabolical pro- ceeding, and is very rightly scheduled as a crime. The destructive action of sulphuric acid on vegetable tissue is seen when a drop falls on wood. The latter turns black and has a charred appearance, just as if it had been burned. Sulphuric acid is characterised by an extraordinary fondness for water. If cold sulphuric acid is added to cold water in a glass vessel, the warmth of their meeting is quite remarkable, and the vessel becomes too hot to hold. Further, if a dish containing a little sulphuric acid is left exposed to the air, the bulk of the liquid gradually increases, and if left long enough the dish would overflow, the reason being that the sulphuric acid absorbs from the air as much moisture as possible, and so becomes diluted. I he affinity of sulphuric acid for water is much utilised by chemists in order to render gases absolutely free from moisture. A current of hydrogen which is being evolved by the action of a metal on hydrochloric acid comes off fully charged with water vapour, but if it is made to bubble through sulphuric acid, the water molecules are seized by the acid and the hydrogen is obtained dry. So 85