Page:The chemical history of a candle.djvu/200

198 kind, the parts being held together, not with interstices, not with porosity, but so continuous that no fluids can pass between them; and, as Dr. Wollaston beautifully shewed, a globule of platinum fused by the voltaic battery and the oxy-hydrogen blowpipe, when drawn into a wire, was not sounder or stronger than this wire made by the curious coalescence of the particles by the sticking power that they had at high temperatures. This is the process adopted by Messrs. Johnson and Matthey, to whose great kindness I am indebted for these ingots and for the valuable assistance I have received in the illustrations.

The treatment, however, that I have to bring before you is of another kind; and it is in the hope that we shall be able before long to have such a thing as the manufacture of platinum of this kind, that I am encouraged to come before you, and tell you how far Deville has gone in the matter, and to give you illustrations of the principles on which he proceeds. I think it is but fair that you should see an experiment shewing you the way in which we get the adhesion of platinum. Probably you all know of the welding of iron: you go into