QUANTITATIVE SEPARATION OF LITHIUM. 



13 



by decantatioii and thon on the lilter with the precipitatmg reagent. 

 The litliiiim fluorid was converted into sulphate and weighed. The 

 fdtrate, amounting usually to from 30 to 40 cc, was measured and 

 4 mg added to the weight of lithium sulphate for each 7 cc of the 

 fdtrate and wash water. Carnot gave some very good results obtained 

 in the separation of lithium from a mixture of lithium <'arbonate, 

 sodium carbonate, and potassium nitrate. For the determhiation of 

 lithium in mineral waters ^ he removed the iron, silica, sulphate, 

 magnesium, barium, calcium, and ammonium, leaving the alkahne 

 chlorids vnth some magnesium, and verified the absence of lithium 

 from each precipitate by the spectroscope. The mixed cldorids 

 were extracted with alcohol to separate the lithium with some so(hiim 

 and potassium from the main part of the sodium and potassium. 

 When the residue was free from lithium the alcohohc solution was 

 evaporated down, the residue taken up with water, and the lithium 

 separated as fluorid. The magnesium with the lithium sulphate 

 was precipitated as ammonium magnesium phosphate, ignited, 

 weighed as pyrophosphate, calculated back to magnesium sulphate, 

 and the weight subtracted to obtain the weight of lithium sulphate. 

 Waller,^ in the determination of the lithium in some well-known 

 waters made use of Carnot's method as a check on the Gooch method. 

 He found that from amounts of salts as large as one or two grams 

 the amyl alcohol extraction was not satisfactory. In two lots he 

 found on the first extraction 0.2400 gram and 0.2.354 gram of lithium 

 sulphate, and in the insoluble part 0.0974 gram and 0.0943 gram. 

 The writers have often extracted the lithium chlorid from quantities 

 of other alkahs amounting to over a gram and have found very slight 

 spectroscopic traces in the insoluble part after two extractions. In 

 the determination of lithium in one water the following results were 

 obtained in two lots: 



Separation of lithium by two extractions of mixed chlorids. 



When the other chlorids separated from a solution containing 

 nearly 0.001 gram of lithium chlorid per cc, it was not surprising that 

 nearly 2 grams of salts should carry down 1 or 2 mg of lithium chlorid. 

 When, however, as on the second extraction, the separation of the 



1 Bull. soc. chim. Par., \m), (3) /.• 28:M). 



» .T. Amer. Chem. Soc, 1890, It- 214. 



