566 PRINCIPLES OF CHEMISTRY 



metals which are analogous to sodium, they all give such very volatile 

 salts and such very characteristic spectra that the least traces of them 38 

 are discovered with great ease by means of the spectroscope. For 

 instance, lithium gives a very brilliant red coloration to a flame and 

 a very bright red spectral line (wave length, 670 millionths mm.), which 

 indicates the presence of this metal in admixture with compounds of 

 other alkali metals. 



Lithium, Li = 7, is, like potassium and sodium, somewhat widely 

 spread in siliceous rocks, but only occurs in small quantities and as 

 mere traces in considerable masses of potassium and sodium salts. Only 

 a very few minerals contain more than traces of it. 39 The compounds 

 of lithium are in all respects closely analogous to the corresponding 

 compounds of sodium and potassium ; but the carbonate is sparingly 



and their component elements, &c. ; but owing to the mutiplicity of the spectral lines 

 proper to many elements, and (especially in the ultra-red and ultra-violet ends of the 

 spectrum) the existence of lines which are undistinguishable owing to their faintness, 

 and also owing to the comparative novelty of spectroscopic research this subject cannot 

 be considered as in any way perfected in any of its branches. 



58 In order to show the degree of sensitiveness of spectroscopic reactions it will be 

 enough to cite the following observation of Dr. Bence Jones. If a solution of 3 grains of 

 a lithium salt be injected under the skin of a guinea-pig, then, after the lapse of four 

 minutes, lithium may already be discoverved in the bilo and liquids of the eye, and, 

 after ten minutes, in all parts of the animal. 



39 Thus spodumene contains up to 6 p.c. of lithium oxide, and petoljte, and lepidolitc 

 or lithia mica, about 3 p.c. of lithium oxide. This mica is met with in certain granites 

 in a somewhat considerable quantity, and is therefore most frequently employed for the 

 preparation of lithium compounds. The treatment of lepidolite is carried on on a large 

 scale, because certain salts of lithium are employed in medicine as a remedy for certain 

 diseases (stone, gouty affections), as they have the power of dissolving the insoluble 

 uric acid which is then deposited. Lepidolite, which is unacted on by acids in its 

 natural state, decomposes under the action of strong hydrochloric acid after it has been 

 fused. After being subjected to the action of the hydrochloric acid for several hours all 

 the silica is obtained in an insoluble form, whilst the metallic oxides pass into solution 

 as chlorides. This solution is mixed with nitric acid to convert the ferrous salts into 

 ferric, and sodium carbonate is then added until the liquid becomes neutral, by which 

 means a precipitate is formed of the oxides of iron, alumina, magnesia, iV'c., as insoluble 

 oxides and carbonates. The solution (with an excess of water) then contains the chlo- 

 rides of the alkaline metals KC1, NaCl, LiCl, which do not give a precipitate with 

 sodium carbonate in a dilute solution. It is then evaporated, and a strong solution of 

 sodium carbonate added. This precipitates lithium carbonate, which, although soluble 

 in water, is much less so than sodium carbonate, and therefore the latter precipitates 

 lithium from strong solutions as carbonate 2LiCl + Na 2 CO 5 = 2NaCl + Li 2 CO 5 . Lith in in 

 carbonate, which resembles sodium carbonate in many respects, is a substance which is 

 very slightly soluble in cold water and is only somewhat soluble in boiling water. In 

 this respect lithium forms a transition between the metals of the alkalis and other 

 metals, especially the metals of the alkaline earths (magnesium, barium), whose carbo- 

 nates are only sparingly soluble. Oxide of lithium, Li 2 O, may be obtained by heating 

 lithium carbonate with charcoal. Lithium oxide in dissolving gives (per molecule) 

 26000 heat units ; but the combination of Li 2 with O evolves 140000 calories that is, 

 more than Na^O (100000 calories) and K 2 O (97000 calories), as shown by Beketoff 

 <1887). 



