Chemistry and Physics, 111 



needle. Acids attack It strongly. From its extreme hardiie^s manganese 

 appears ^vell adapted to various purposes, A fragment with a sharp edge 

 w 11 serve to cut glass like diamond. The metal may be c st in moulds 

 like iron, and the high polish which it assumes may rend r it available 

 for the mirroi-s of telescopes, etc. In conclusion the author directs atten- 

 tion to the probability that manganese will form useful alloys. — Comptes 

 Rendus^ xliv, 630. 



4, On crystallized Chromium and its alloys, — At the same sitting of 

 I the Academy at w^hich Brunner's memoir was read, Fremy communicated 



a note on the preparation of manganese and chromium by a somewhat 

 different process, namely, by passing the vapor of sodium over the anhy- 

 drous chlorids. The decomposition takes place in a porcelain tube heated 

 to redness, the vapor of sodium being conveyed by a current of hydrogem 

 Chromium as thus obtained presents itself in the form of small cubic crys- 

 tals, which are very hard and brilliant, and which resist the action of the 

 strongest acid, and even of aqua-regia. The alloy of chromium and iron 

 crystallizes in long needles and scratches the hardest bodies, even tem- 

 pered steel. The author finds that the sesquioxyd of chromium may 

 easily be fused at a forge heat and yields a very hard black crystalline 

 mass which may perhaps find useful applications. 



5. On some general methods of preparing the elements, — H. Sainte 

 Claire Deville, in connection with the communications of Brunner and 

 Fremy, has offered some interesting remarks upon the subject which is 



\ now attracting so much attention in France and Germany, the prepara- 



tion of the rarer metals. Deville is of opinion that the best mode of 

 preparation consists in igniting the oxyd with carbon, taking care to em- 

 ploy an excess of oxyd. It is however .an indispensable precaution to 

 fuse the metal in a crucible of lime or magnesia. Crucibles of clay, por- 

 celain, &c., are like borax partially reduced by many metals and even by 

 platinum. The silicon produced considerably increases the hardness and 

 fusibility of the metal. In a ciaicible of lime the oxyd of chromium or 

 manganese in excess is absorbed by the lime, forming a chromite or man- 

 ganite which fuses with great difficulty, but which removes fron^ the 

 metal all traces of carbon and silicon. The fusibility of the metal dimin- 

 ishes as their purity increases, and the author found chromium less fusible 

 than platinum, Deville remarks that manganese, as prepared by Brun- 

 ner's method, may still contain carbon. Sodium prepared from the car- 

 bonate always contains more carbon, and moreover, from its porosity it 

 frequently retains naphtha, which leaves a carbonaceous residue when 

 heated. The employment of Hessian- crucibles is also objectionable, as 

 silica is easily reduced by sodium, especially in the presence of the fluo- 

 ^ rids. In this manner the author explains the differences between Brun- 



I ner's manganese and that prepared by himself, w^hich is less fusible than 



iron and decomposes water at ordinary temperatures. The employment 

 of sodium, on the other hand, presents great advantages when we wisli 

 to obtain an element in a crystallized state. In this case the sodium may 

 often be replaced by aluminum, as for example, in preparing silicon, 

 titanium, zirconium, and boron. In the case of the sesquichlorids of zir- 

 conium, aluminum or chromium, it is always well to make the sodium 

 react upon the double chlorids which these bodies form with chlorid of 



