10 THE DETERMINATION OF LITHIUM. 



of lithium chlorid to decompose on drying, forming hydroxid, which, 

 he said, was not soluble in ether-alcohol. The tri-basic phosphate 

 is soluble one part in 2539 parts of cold water and in 3920 parts of 

 water and ammonia. In ammonium clilorid solution the precipitate 

 was very soluble. 



Mayer stated that Rammelsberg obtained from 100 parts of 

 lithium chlorid from 143.6 to 89 parts of mixed phosphate. The 

 higher results he attributed to the sodium not washed out, and the 

 lower ones to the lithium carbonate obtained. In nine analyses 

 carried out to test the phosphate method from 98.9 to 100.6 per 

 cent with an average of 99.61 per cent was obtained. 



In a still later article ^ Rammelsberg insisted that the phosphate 

 precipitate always contains sodium, though Mayer ^ claimed this 

 statement to be untrue. Some years later in a paper on the consti- 

 tution of lithia micas, Rammelsberg ^ reviewed his results obtained 

 since 1850, when he first used ether-alcohol in some tourmahne 

 analyses and obtained values lower than those obtained by other 

 analysts, who used the phosphate method of precipitation. He 

 noted the loss of lithium in case the mixed chlorids were extracted 

 only once and recommended that the residue be dissolved, dried, 

 and extracted again. He tested his potassium platinic chlorid 

 precipitates by igniting, weighing the 2KC1-|-Pt, washing out the 

 potassium-chlorid, and weighing the platinum and found the pro- 

 portion of platinum less than that required for the theoretical com- 

 position of potassium platinic chlorid (K.PtCle) and therefore argued 

 that no lithium was present, as lithium would have made the ratio 

 of platinum larger. He did not note the testing of any of his residues 

 or precipitates with the spectroscope. In another observation * on 

 the lithium determination, he gave an analysis of a phosphate pre- 

 cipitate where the solution was strongly alkaline with sodium hy- 

 droxid before evaporation, and yet the precipitate gave phosphoric 

 acid (P2O5) 60.41 per cent, lithium oxid (LijO) 37.14 per cent, sodium 

 oxid (NajO) 1.51 per cent; total, 99.06 per cent. When more sodium 

 hydroxid was used the precipitate contained more sodium. 



Jenzsch ^ in some analyses of minerals found a lithium platinic 

 chlorid precipitated with his potassium platinic chlorid. He found 

 it hard to extract all the lithium with ether-alcohol, and if he continued 

 •the treatment until all the lithium was in solution he had weighable 

 quantities of sodium and potassium also dissolved. He made some 

 experiments on the volatility of the lithium chlorid and sulphate 

 and noted the much greater volatility of the chlorid and the tendency 

 of the lithium chlorid to decompose and change into the hydroxid, 

 which makes uncertain the weight of the mixed chlorids. 



1 Pogg. Ann., 1857, 102: 441-3. •• Pogg. Ann., 1879, (2) 7: 157. 



« Ann. Chem. Pharra., 1856, 98: 1!«. ^ pogg. Ann., 1858, lOi: 102. 



» Pogg. Ann., 1879, (2) 7: 136-146. 



