

Chemical Science. 411 



37. ON MAGNESIUM. (Justus Liebig.) 



The Annales de Chimie, of March, 1830, contain a paper by M. 

 Bussy, on magnesium, which he obtained by the action of chloride 

 of magnesium on potassium ; the properties of this metal appeared 

 to M. Liebig to be so very extraordinary, that he was induced to 

 make some experiments on it. 



M. Bussy's method of obtaining the chloride consists in passing 

 chlorine gas over a mixture of magnesia and charcoal, whilst in a 

 state of ignition ; it may, however, also be obtained by evaporating 

 equal parts of the muriates of ammonia and magnesia, and heating 

 the dry residuum in a platina vessel, until the muriate of ammonia is 

 completely expelled, and the mass becomes fused. The remain- 

 der is chloride of magnesium, and if left to cool, forms white trans- 

 parent leaf- like crystals. 



In order to reduce the chloride of magnesium, from about 10 to 

 20 small globules of potassium are put into a glass tube, three or 

 four lines in diameter, the chloride is placed over them, and heated 

 over charcoal, until it begins to flow ; the tube is then slightly in- 

 clined, so that the potassium runs through the chloride, which is thus 

 reduced to magnesium with the evolution of light. If the mass, 

 when cold, be treated with water, a large quantity of small metallic 

 globules will be collected at the bottom of the vessel ; they are of a 

 silver-white colour, have much metallic lustre, and, though malleable, 

 are very hard ; neither cold nor hot water acts on them. If mixed 

 with chloride of potassium, and heated in a crucible, they may be fused 

 into one mass, and their point of fusion does not apparently exceed 

 that of silver. The metal is dissolved by diluted acetic acid, as well 

 as by sulphuric and nitric acids, with the evolution of hydrogen gas, 

 and sulphurous and nitrous vapours: the solutions are found to 

 contain no other oxide besides magnesia. When heated in atmos- 

 pheric air or oxygen gas, the metal burns with the most vivid light ; 

 the vessel is covered with magnesia ; and at the place where the 

 metal was, a black spot remains, which seems to be silicium, as it 

 was not destroyed by boiling hot acids. Sulphur did not seem to 

 unite with the metal, when both were fused together. The solution 

 in sulphuric acid yielded, on evaporation, crystals of sulphate of 

 magnesia*. 



38. ON THE EXPANSION OP BISMUTH AND ITS ALLOYS DURING 

 CONGELATION. (Professor Marx, of Brunswick.) 



Bismuth is known to be a very remarkable instance of apparent ex- 

 ception from the general rule, that fluids contract when becoming 

 solid ; and it corresponds with water in this respect also, that it com- 

 municates this property to other bodies, particularly metals, if it 

 forms a certain proportion of the alloy. Where the maximum of 



* Poggeudorf 's Aunalen. 



