The advantage of warm clothing : no. 5 of deposits in the Savings' Bank of Wisdom, made in behalf of working men and women.

Date:
[between 1850 and 1859?]
Catalogue details

Licence: Public Domain Mark

Credit: The advantage of warm clothing : no. 5 of deposits in the Savings' Bank of Wisdom, made in behalf of working men and women. Source: Wellcome Collection.

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    and in general usefulness. These prime assistants of the chemists are tire and water. The water is employed to dissolve substances whose little particles it is desired to bring closely together. When two different liquids thus formed are mixed, all the particles in the two come together and act upon one another. Fire is used to soften substances, and loosen the hold of their little particles upon each other, so that they may afterwards be readily mixed together. Water dissolves bodies ; that is, makes them liquid by uniting them with itself. Eire melts bodies ; that is, makes them liquid without the aid of water. Now there is one object which the chemists often have in view, when they put different kinds of sub- stances together, in a dissolved or liquid state, in the chambers and vessels of their laboratories; that is, to get something out of those substances, which was before hidden away in them, in order that they may turn that something to practical use. Thus the chemist mixes together saltpetre, sulphur, and char- coal in jthe right proportions to make gunpowder. Then haying rammed a charge of the gunpowder down into the tube of a gun, with a bullet on the top of a charge, he applies a spark to the gunpowder, and makes it change into smoke and vapour. Some- thing which was hidden away in the gunpowder ceases to be concealed when it is changed into smoke and vapour, and becomes active enough to be able to drive the bullet out of the muzzle of the gun with a force that carries it through the air for a mile, and perhaps then buries it deep in the ground, or in a plank of wood. This is an instance of the way in which chemists produce motion, by changing the state and condition of material substance. 1 had occasion the other day to watch a still more interesting example of this strange result of the chemist's skill. In a chemist's laboratory, prepared for a particular service, I saw several small chambers of metal, half copper and half zinc, into which wer©