260 Prof. R. Bunsen on Rhodium. 



for the reception of any moisture that may pass over. In the 

 flask a chlorine is disengaged, and is dried by passing through 

 sulphuric acid in b ; after passing through the series of flasks, 

 it terminates in the chlorine-condenser, /, which is filled with 

 wood-charcoal and solid hydrate of lime. Under each copper 

 capsule is a single burner with a good draught, or, what is 

 better, a three-jet Bunsen's burner. When all atmospheric air 

 is expelled, all the burners are lit, and a brisk, but not violent, 

 disengagement of chlorine is kept up for about three hours. 

 The chlorine is at first so completely absorbed, that no bubble of 

 gas escapes from the tube leading into the condenser when it 

 dips under water. The successive action in the individual flasks 

 is manifested by a deposition of perchloride of iron in the neck, 

 and may be considered finished when this sublimate has about 

 the same amount and appearance in each. On taking the appa- 

 ratus to pieces, there is found in the flasks (the necks are cleaned 

 from perchloride by bibulous paper) a dark rusty-brown mass not 

 much agglomerated, which dissolves on the addition of water 

 with great disengagement of heat. In six of the flasks, which 

 may be used six or eight times for the same purpose, 100 to 120 

 grms. of platinum-metals may be attacked at once. The residue 

 which remained unattacked weighed 13*7 grms., and after reduc- 

 tion with hydrogen 1 1*4 grms. By means of zinc, 4*5 grms. pla- 

 tinum-metals was extracted, which were insoluble in nitric acid, 

 and which contained all the ruthenium present in the original 

 material. Hence, of 65 grms. of platinum-metals in three 

 hours, and by means of four ordinary non-luminous three-jet 

 burners, 57 grms., or 93 per cent., was attacked by a current 

 of chlorine, in the production of which 415 grms. pyrolusite of 

 of 85 per cent, was dissolved in hydrochloric acid. 



The mass attacked by chloride of barium and dissolved in 

 water contains, besides rhodium and iridium, chiefly copper, 

 lead, iron, zinc, and small quantities of the other platinum-me- 

 tals. The liquid is boiled, and the baryta removed by means of 

 sulphuric acid. If specimens are taken by means of a capillary 

 tube from the edge of the heated liquid in the manner mentioned 

 under palladium, in a few minutes, by alternate addition of sul- 

 phuric acid and chloride of barium, any excess, either of barium 

 or of acid, may be removed to within a hundred-thousandth of 

 the entire saline mass. 



In order to obtain the platinum-metals free from any impuri- 

 ties present in the solution, they are precipitated by hydrogen. 

 For this purpose about a litre of the liquid is brought into a flask 

 of twice the capacity, boiled for a time, and, after removing the 

 lamp, the aqueous vapour is displaced by a rapid current of hy- 

 drogen ; for this purpose it enters from a Dobereiner's apparatus 



