240 Messrs. F. C. Calvert and E. Johnson on Alloys. 



a dense and compact condition ; and to prepare alumina on 

 a large scale, freeing it fi'om those substances which would act 

 injuriously on the preparation of the metal, would be attended 

 with great difficulties. 



The buttons of aluminium which I have prepared are so mal- 

 leable that they may be beaten and rolled out into the finest 

 foil without cracking on the edges; they have a strong metallic 

 lustre. Some small pieces, not globular, however, which were 

 found at the bottom of the crucible and occasionally adhering to it, 

 cracked on being hammered, and were diiFerent in colour and 

 lustre. They were evidently not so pure as the greater number 

 of the globules and contained iron. 



On sawing through a larger button of aluminium weighing 

 3'8 grms., it could readily be observed that the metal for about 

 half a line from the exterior was brittle, while in the interior it 

 was soft and malleable ; sometimes the interior of the globules 

 contained concavities. 



With Deville I have occasionally obtained the aluminium 

 crystalline. A large button became striated and crystalline on 

 the niidcr side on cooling. Deville believes he has observed 

 regular octahedra, but does not state this positively. Accord- 

 ing to my brother's examination, these crystalline indications do 

 not belong to the regular form. 



As I chanced on one occasion to attempt the fusion of a large 

 button of rather impure aluminium after flattening it out, with- 

 out a flux, I observed before the heat was sufficient to fuse the 

 mass small globules sweating out of the surface. The impure 

 aluminium being more infusible than the pure metal, the latter 

 expands on fusing, and comes to the surface. A similar phse- 

 nomeuon has been remarked by Schneider with impure bismuth. 



I have mentioned above that kryolite is used under the name 

 of mineral soda here in Berlin, for the preparation of soda-ley, 

 which, on account of the alumina it contains, is admirably adapted 

 to the manufacture of soap. In fact, powdered kryolite is com- 

 pletely decomposed when boiled with quicklime and water. 

 The fluoride of calcium formed contains no alumina, which is 

 all dissolved in the caustic soda solution, and this, on its side, is 

 free from fluorine or contains only a very minute trace. 



XXX. On Alloys. By F. Grace Calvert, F.C.S., M.R.A. of 

 Turin, ^c. ; and Richard Johnson, M.Ph.S. Manchester^. 



THERE are few subjects in chemistry which have been less 

 examined than alloys, and yet when we reflect on the im- 

 portant services which they render to manufactures and the arts, 

 * Communicated by the Authors. 



