METEORITES, N.S.W. 345 



precipitate thrown down from the hydrochloric acid solu- 

 tion of the meteorite by hydrogen sulphide, although 

 these metals in the free condition are usually regarded as 

 being insoluble in hydrochloric acid free from chlorine; they 

 may, however, be present in the meteorite in the form of 

 compounds or alloys soluble in hydrochloric acid. The gold 

 and platinum-like metals were separated from the brown 

 precipitate thrown down by hydrogen sulphide, by igniting 

 it (so as to drive off the sulphur) and then repeatedly 

 grinding the residue with water in an agate mortar as 

 above described, the oxides of the lighter metals were 

 gradually washed off and the free metals obtained in the 

 form of yellow and white spangles, insoluble in hot nitric 

 acid and therefore presumably gold and one or more of the 

 platinum metals ; the quantities obtained were too small 

 to weigh; although the process of grinding in an agate 

 mortar is an exceedingly delicate test, far more so than 

 the wet tests, yet some of the metallic particles are prob- 

 ably lost, since it is difficult to prevent the very thin 

 spangles of the precious metals from floating off during 

 the process of washing. The results are not those of a 

 single experiment as is shown by the following : — 



Experiments — (a) 20 gms. of the sawdust from the mete- 

 orite were dissolved in hydrochloric acid, the insoluble 

 residue on grinding left a few small specks of both yellow 

 and white metals insoluble in nitric acid, and the hydrogen 

 sulphide precipitate from the solution, after ignition, 

 yielded specks of a white metal insoluble in nitric acid; 

 therefore presumably both gold and platinum are present. 



(b) 20 gms. of sawdust treated as above, also yielded 

 what appeared to be gold and platinum in the insoluble 

 residue, but none was found in the SH 2 precipitate. 



(c) 20 gms of sawdust yielded a few specks of a yellow 

 metal which were insoluble in nitric acid, therefore pre- 

 sumably gold. 



