M. Stas on the Determination of Atomic Weights. 203 



chloride of potassium (c), though this least of all. In these 

 cases the sodium comes in from the atmosphere. Ten grammes 

 of each chloride of potassium were weighed in a platinum boat 

 and volatilized in a current of nitrogen in a porcelain tube, (a) 

 left 0-0056-0-006 per cent, of residue (silica); (b) = 0-00-15 

 -0015 per cent.; (c) =0-025 and 0-0048 per cent. 



The mean of all experiments is, 100 parts of KC1 give 



135*6423 parts of nitrate of potassium. 



Chloride of sodium. — (a) Finely pulverized bicarbonate of so- 

 dium was lixiviated, ignited, dissolved in hot water, the solution 

 rapidly cooled, and the fine salt deposited well washed out. It 

 was then thrice recrystallized, saturated withhydrochloric acidgas, 

 the solution evaporated in a platinum retort after the addition 

 of some sal-ammoniac, and ignited. The salt was then again 

 dissolved, poured off from the separated silica and alumina, 

 evaporated with the addition of ammonio-chloride of platinum 

 and fused. It was, finally, again dissolved with the addition of 

 sal- ammoniac, and, at length to expel all sal-ammoniac, kept in a 

 state of fusion for a long time. 100 parts of chloride of sodium 

 gave 145*453 parts Na NO 3 . 



(b) The chloride of sodium (a) was dissolved, mixed with bi- 

 chloride of platinum, by which no precipitate was formed, evapo- 

 rated and heated until decomposition set in. Only -£§ of the 

 residue was dissolved ; the solution, evaporated till a crust began 

 to form, was then rapidly cooled, and the salt deposited washed 

 with ice-cold water. From the mother-liquor two crystallizations 

 of sodio-chloride of platinum were obtained by similar treatment. 

 Thesolutionof the three portions was precipitated with chemically 

 pure sal-ammoniac, and the solution evaporated after the addi- 

 tion of some ammonio-chloride of platinum, and ignited. The 

 residue, again dissolved, was evaporated and fused. 100 parts 

 of chloride of sodium furnished 145-468, 145*465, 145*459, and 

 145-443 of nitrate of sodium. The mean of the whole = 145*4526. 



The chloride of sodium («), volatilized in a current of nitrogen, 

 left 0*0047 per cent, of silica, with lime and soda; (b) left 0*0035- 

 0*0045 silica, with lime and soda. 



Lithium. — Purified carbonate of lithium was dissolved in hydro- 

 chloric acid, and freed from lime and magnesia by sulphuretted 

 hydrogen, oxalate of ammonium, and baryta-water. The baryta 

 was removed by sulphate of ammonium, the filtrate evaporated, and 

 the ammonia-salts expelled. The fused residue was dissolved in 

 absolute alcohol, mixed with its volume of ether, and the solution 

 treated by a freezing-mixture. The chloride of lithium deposited 

 still contained much sodium. Nor from nitrate of lithium can 

 all sodium be removed by ether- alcohol. The Li CI was now dis- 

 solved, mixed with neutral carbonate of ammonium, and the mix- 



