S. L. Penfield — Canfieldite, a new Germanium Mineral. Ill 



filtrate the sulphur was precipitated as barium sulphate, which 

 was purified by fusion with sodium carbonate, reprecipitated 

 and weighed. For the determination of germanium another 

 portion of two grams was oxidized by nitric acid with the 

 addition of a little sulphuric acid. After removal of the large 

 excess of nitric acid by evaporation, the residue was dissolved 

 in warm water, with addition of some nitric acid if necessary, 

 the silver precipitated with ammonium thiocyanate and re- 

 moved by filtration. The filtrate contained the germanium 

 together with no acid which forms with it a volatile compound. 

 It was evaporated in a platinum dish, the nitric acid present 

 serving to completely destroy the ammonium thiocyanate, and 

 the excess of sulphuric acid was finally driven oif by heating. 

 The residue thus obtained was covered with a little strong 

 ammonia into which hydrogen sulphide was conducted. Under 

 this treatment the germanium oxide dissolved, while all heavy 

 metals, except those which form sulpho-salts soluble in am- 

 monium sulphide, were left undissolved. In this particular 

 case a very small quantity of a black sulphide remained ; it 

 was filtered off, ignited and weighed. It is assumed to be a 

 mixture of zinc and iron oxides, resulting probably from 

 admixed sphalerite and pyrite. The filtrate containing the 

 germanium was collected in a weighed platinum crucible and 

 evaporated on the water bath. The residue was oxidized by 

 strong nitric acid, the excess of which was removed by evapo- 

 ration. The crucible, placed inside of a porcelain one, was 

 then ignited, gently at first, finally to the full extent of a ring 

 burner, then weighed and the germanium determined as Ge0 2 . 

 On further ignition the weight was found to be constant, nor 

 did it change by heating to full redness. When heated in a 

 current of ammonia and air, to remove sulphuric acid, the 

 weight diminished very little ; thus in one experiment it fell 

 from 0*1535 to 0*1525 grs., showing that a gentle ignition is 

 sufficient to practically expel all of the sulphuric acid. By 

 heating to a bright redness in a current of ammonia and air 

 the germanium oxide suffered reduction to the metallic state. 

 To show that the germanium oxide was pure and especially to 

 prove the absence of arsenic and antimony the following tests 

 that were made may be mentioned. Rather large quantities 

 of the mineral, when roasted in the open tube gave no subli- 

 mate. An acid solution of the oxide gave upon addition of 

 hydrogen sulphide a white precipitate, which when collected 

 on a filter showed only a pale tinge of yellow. Also the oxide 

 obtained in the analysis when dissolved and brought into a 

 Marsh apparatus gave only a most minute and unweighable 

 blackening on the walls of the tube, which on ignition in the 

 air changed to a scarcely perceptible white oxide resembling 



