l'\\i!(^iHAKsox. - — '/'/?(' Flatiiium Gravels of Orepukl. 'ill 



whole was inquavted and parted in nitric acid as before, caro being taken 

 to use only a minimum of silver to prevent any loss of other metals which 

 might be present. After parting and drying, the bead was again weighed. 

 Its weight amounted to 0-0195 grain. This strongly suggests that no metal 

 except gold was present in the rock, for, although a small difference in winght 

 (0-0005) was obtained, this could never be regarded as con(,-lusive. 



To remove, however, all element of doubt with regard to the presence or 

 otherwise of platinum in the rock, recourse was had to the following method : 

 A large mass of perfectly fresh rock weighing over 4,000 grammes (nearly 

 10 lb.) was taken and carefully powdered. The pestle and mortar used was 

 first rendered perfectly clean, and the preliminary crushing of the rock was 

 done in new cloth, so that all danger of introduction of any foreign materials 

 whatever was done away with. After crushing had been gone on with 

 until the powder was fine enough to go through a 6()-mesh sieve it was 

 panned off. By this means all the lighter portion of the powder was gradu- 

 ally carried off, and ultimately there was left a mass of black material about 

 30 grammes in weight. This was carefully examined by means of a micro- 

 scope for any trace of the silvery metal, but none was found. Since, how- 

 ever, the result of most observations on the occurrence of the metal 

 in igneous rocks tends to show that it is present in them in exceedingly 

 fine division, the concentrates were subjected to a process as follows : A 

 quantity of aqua regia was added to the porcelain vessel containing the 

 residue, and the liquid was evaporated to dryness on a water-bath. This 

 process was carried out two or three times, to insure the solution of any 

 metal present. The residue (from the evaporated solution, not the original 

 residue) was then twice treated with sulphuric acid, and again evaporated 

 to dryness on a water-bath. This residue was taken up with absolute 

 alcohol and water, filtered, more alcohol was added, and to the clear solu- 

 tion was added ammonium-chloride crystals in excess. The solution was 

 slightly warmed to dissolve the crystals, and put aside for twenty-four hours. 

 On examination at the end of that time no trace of a precipitate was visible, 

 and, though the liquid was again filtered, absolutely no trace of the yellow 

 chloroplatinate was found. Care, of course, had been taken not to have 

 too much liquid when the ammonium-chloride was put in, for in that case a 

 small quantity of platinic chloride, even if present, might not be precipitated. 



From results got from assays, and from qualitative tests for the metal, 

 we are forced to the conclusion that it does not occur naturally in the 

 gabbro. There is, of course, the very remote possibility that the metal 

 occurs so sparsely distributed in the rock that the actual piece taken really 

 contained none. The assays, however, were all done on pieces of rock 

 broken from different places, and if there had been any present we should 

 have expected a small, yet distinct, indication. It is unlikely, too, that a 

 piece of rock 10 lb. in weight from the heart of the claim should contain no 

 trace of metal if it were really present in the rock. 



Where, then, does it come from ? The clay-slate formations of the 

 range can be dismissed as far as the claim is concerned, for the present 

 stream does not flow through them, nor could it have been possible for 

 even a large stream to have done so. The cause of the stream being larger 

 was not a greater length, of course, than it now has, but an elevation of 

 the land causing a greater rainfall and thus increasing the water-supply 

 without lengthening the course to any extent. The stream everywhere 

 flows through gabbro rocks until reaching the plains. 



