..vj M. Troost on Lithium andiis Compounds. 121.1 



them the general formula MO, H0 + 12(M0, SbOH^HO), in 

 which M expresses the positive metal, and n the number of atoms 

 of water. This relation of 13 equivalents of base to 12 equiva- 

 lents of acid was so unusual, that the foriuuke were generally- 

 received with some mistrust. But on calculating HefFter's results 

 with the new equivalent of antimony, numbers are obtained 

 which agree very v/ell with the general formula MO, SbO^ + nHO, 

 thus establishing their relation with a large class of salts. 



Mallet* has recently made a determination of the atomic 

 weight of lithium. He estimated the chlorine in a A-ery pure 

 specimen of chloride of lithium prepared from spodumene, and 

 took much larger quantities than had hitherto been done. As 

 the mean of three veiy closely agreeing experiments, he obtained 

 the number 86'89, or 6 "95 on the hydrogen scale. This number 

 is higher than that found by Berzelius, 6-54, and which has 

 hitherto been usually adopted ; but jMallet shows that the method 

 used by Berzelius was not entirely free from objection. ]\Iallet 

 points out, that if we take the mean of the equivalents of lithium 

 and potassium, we get 



6-93 + 39-18 



=23-06, 



which is almost exactly the equivalent of sodium, 23-00, as 

 determined by Pelouze. 



Troost t has published some experiments on lithium and its 

 compounds. The method by which he obtained the lithia salts 

 is suitable for their preparation on a large scale. It con- 

 sists in heating in a crucible in a good wind-furnace, lepi- 

 dolite mixed with carbonate and sulphate of baryta in certain 

 proportions. At the bottom of the crucible there is obtained a 

 glass pei-fectly melted but viscous, and above a very fluid mass, 

 which may readily be pom-ed off v, hilc hot. This consists of a 

 mixture of sulphate of baryta, potash and lithia. By treating 

 this with water, the alkaline sulphates are dissolved out. Lithia 

 may also be obtained from petalite by the same process, if a 

 sufficient quantity of alkalies be added to make the whole pro- 

 portion the same as in lepidolite. 



Troost obtained lithium by Bunsen's method. He also made a 

 great many attempts to procure it by the method used by Deville 

 in the preparation of sodium. To this end he heated a mixture 

 of carbonates of lithia, chalk, and charcoal to a white lieat for 

 several hours. It was found, however, that lithium was not volatile. 

 By acting on chloride of lithium with sodium, an alloy of lithium 



* Silliraan's Journal, November 1, 1856. 

 t Comptes Rtndus, November IC, 1850. 



