350 i)r. Gmelin's Analysis of Pefa/ite, [MAy, 



collections of small needles, usually radiating from a common 

 centre. 



Double Salts. 



Tartrate of Lifhia-and-Pofash.— U the excess of acid of 

 bitaiti'ate of potash be saturated by means of carbonate of lithia^ 

 we obtain, by spontaneous evaporation, a salt which forms lai'ge 

 crj^stals, having the shape of four-sided prisms terminated by 

 pai-allelogTams, with angles A'ery nearly right. The diagonals 

 of these terminal faces are distinctly marked, and the four 

 triangles formed by means of them are streaked paruUel to the 

 edges of these faces. I dissolved this salt repeatedly in water, 

 and crystallized it again, and always obtained the very same kind 

 of crystals ; so that, by this property, lithia seems to be very well 

 characterized. This salt dissolves readily in water, and has a 

 saline and scarcely bitter taste. When exposed to the air, it 

 effloresces shghtly, and only on the surface. 



Tartrate oj Lithia-avd-Suda. — Bitartrate of soda was neutra- 

 lized by means of carbonate of lithia. By spontaneous evapora- 

 tion, the liquid deposited long rectangular four-sided prisms, 

 frequently terminated by an oblique face. This salt dissolves 

 with facility in water, and effloresces only slightly and on the 

 surface, its taste is purely saline, and not strong. 



Sulphate of Alumiiia-atid-lJlliia. — No crystallized salt analo- 

 gous to alum can be formed by combining these substances 

 together. I mixed three diiierent times together solutions of 

 pure sulphate of alumina and sulphate of lithia, and subjected 

 the mixture to spontaneous evaporation. I always obtained a 

 white, opaque mass, not crystalirzed. This does not agree with 

 the experiments of Arfvedson, who obtained crystals by the 

 spontaneous evaporation of such a mixture, which had very 

 much the appearance and taste of alum. 



Muriate of Flat iu urn does not foim a double salt with muriate 

 of lithia. Potash and lithia, therefore, may be very well distin- 

 guished from each otlier by means of nmriate of platinum. 



Attempt to procure IJthium the Basis of lAthia. 

 A small portion of caustic lithia still remaining in my posses- 

 sion, I endeavoured to procure from it the combustible substance 

 which constitutes its basis ; but as I was not in possession of a 

 very poweiful galvanic battery, I tried whether I could not form 

 an amalgam of it with mercury. I employed for the experiment 

 182 pairs of copper and zinc plates, the surface of each of which 

 amounted to 3-^ French inches square. The causuc lithia was 

 put into a small platinum cup, and brought by means of water to 

 the consistence of pap. Into this matter a globule of mercury 

 was put, vi hich was brought into contact with the negative pole 

 of the battery; while the platinmn cup was in contact with the 

 positive pfle! The contact was effected by means of platinum 

 wires. 



