113 M. Freray on Metallic Chromium and Manganese. 



Ainorplions boron possesses properties as a reducing agent 

 which place it near carbon. Its affinity for chlorine is so great, 

 that the chlorides of lead, mercnry and silver, are reduced at a 

 high temperature with formation of chloride of boron. Galena 

 is also reduced by boron, lead and sulphide of boron being the 

 products. 



Brunner* obtained metallic manganese by the process by 

 Avhich aluminium is obtained — the reduction of its ilaoride by 

 means of sodium. He brings two parts of fluoride of manga- 

 nese and one of sodium in alternate thin layers into a crucible, 

 presses the two well, covers them with a layer of dry chloride 

 of sodium, and then with a layer of small pieces of fluor-spar 

 to prevent spurting. The crucible with a cover is placed in a 

 wind-furnace and gently heated till the first action is over, which 

 is perceived by a hissing in the crucible, and the issuing from it 

 of a yellow flame ; the crucible is then raised to a bright red heat 

 and maintained in this state for a quarter of an hour, after which 

 all the openings of the furnace are closed to allow the crucible 

 to cool gradually. The manganese is then found melted at the 

 bottom of the crucible. If it is not fused together, it is again 

 melted beneath a cover of chloride of sodium to which one-tenth 

 of saltpetre has been added. 



The manganese thus obtained has the colour of cast iron ; it 

 is very brittle, and so hard that it scratches even the best hard- 

 ened steel, and cuts glass like a diamond. It is capable of a 

 high polish ; does not change at the ordinary temperature in 

 moist air : heated on platinum-foil it tarnishes with the same 

 succession of colours as steel, and by continued heating becomes 

 covered with a coating of brown oxide. It is not attracted by 

 the magnet, and does not attract the magnetic needle. It has 

 the specific gravity 7-138 to 7'20G. Ey the action of strong 

 sulphuric acid in the cold a little hydrogen is disengaged : heated 

 with the same acid, it dissolves with evolution of sulphurous 

 acid. Dilute sulphuric, nitric, hydrochloric, and acetic acids dis- 

 solve it with facility. 



Fremyt prepared metallic chromium and manganese by the 

 action of sodium on their respective chlorides. He caused the 

 vapour of sodium carried in a stream of hydrogen to act upon 

 the metallic chlorides, heated in a porcelain tube to a bright red 

 heat. In both cases the metal separates out in a crystalline 

 form. Frcmy only describes the chromium. Freed from chlo- 

 ride of sodium by washing, it has the form of brilliant crystals 



* Liebig's Annalen, June 1857. Poggendorff' s Annalen, June 1857. 

 t Comptes Rendus, March 23, 1857. Liebig's Annalen, Jime 1857. 



