382 Grandeau, Lefevre, and Than on the Occurrence of Rubidium. 



of purified nitrogen gas. The weight of the magnesium had 

 increased by about 18 per cent. The substance thus obtained 

 had an almost pure yellow colour : it was generally contaminated 

 by the presence of a little magnesia ; for the substance rapidly 

 attracted moisture in the air, forming magnesia and ammonia. 



When this substance was heated with hydrochloric acid, it was 

 decomposed with the formation of chloride of ammonium and 

 chloride of magnesium. The analytical results, after allowing 

 for the magnesia formed, agreed with the formula Mg 3 N. 



Nitride of magnesium forms at ordinary temperatures a 

 greenish mass, which is slowly oxidized to magnesia in dry air, 

 and more rapidly in oxygen. It is rapidly decomposed by water. 

 Acids also decompose it. When heated in carbonic oxide or 

 carbonic acid at a very high temperature, it is decomposed into 

 magnesia with the separation of carbon and liberation of cyanogen. 

 When heated with pentachloride of phosphorus, it forms chloride 

 of magnesium, and a substance which is probably a phosphide of 

 nitrogen, P 3 N 5 . 



The authors found that iron, when heated in a current of 

 nitrogen nearly to its melting-point, increased in weight about 

 2*16 per cent., and when afterwards fused with potash, disen- 

 gaged some ammonia. 



Aluminium also appeared to absorb nitrogen at a very high 

 temperature. 



Chromium, heated in nitrogen to the strongest red heat, in- 

 creased in weight to the extent of 15 to 18 per cent. The pro- 

 duct obtained had the appearance and all the properties of Ufer's 

 nitride of chromium, Cr' 2 N, obtained by the action of chloride 

 of chromium and ammonia. The authors did not succeed in 

 obtaining compounds of nitrogen with tungsten or molyb- 

 denum. 



M. Grandeau* has observed the occurrence of rubidium in 

 the saline residues of beetroot, and in the mother-liquor derived 

 from their treatment for the extraction of chloride of potassium. 

 The specimens examined were from the distillery at Corbehem. 

 M. Lefevre, the proprietor of this establishment, states f that 

 1 hectare (about 2\ acres) produces 40,000 kilogs. of beetroot, 

 which furnish 128 kilogs. of crude potash. Each kilog. of crude 

 potash gives on the average 1 75 gramme of chloride of rubidium; 

 so that 1 hectare produces 226 grammes, or about 7J ounces. 



To obtain the rubidium -salt, the mother-liquor from the pre- 

 paration of nitre in the above manufactory is incinerated with 

 wood shavings, to get rid of sulphur and of some nitre; the 

 carbonaceous residue exhausted with water and evaporated to 



* Comptes Rendits, May 19, 1862. f Ibid. Septembers. 



