Douglas Island news., 1899-06-14
The Douglas Island News,
SIMPLE TESTS.
How to Tell the Presence of Gold Tn Low Grade
 Ores.

| Ores.
 Western firms have offered for sale from time to time portable apparatus for determining gold in minerals, which were supposed to enable the prOspector to decide whether the ore contained any gold or not by the simple operation of dissolving the ore in acids and ad- ding stannous chloride to the solution obtained. It was assumed that the for nation of purple of Cassius would give in all cases sufficient confirmation ot the presence of gold.
 Those who tried this process have discovered, however, that the formation of the purple could not be ascertained with satisfaction in solutions of gold ores containing but little of the precious metal, and have declared the method to be unsatisfactory in such cases.
 At the present status of gold recovery, when ore containing 8 gold to the ton is treated with profit, the knowledge of a reliable and simple method for the determination of the presence of gold is of vital importance. The apparatus required, if at all acceptable to the prospector, should involve but little expense, occupy but little space and do away with the application of heat as produced by spirit lamp, candle or oil stove. In fact, any cumbersome ap- paratus or complicated operation is out of the question for obvious reasons.
 The following methods, which allow of the detection of OOPS OF. of gold to the ton with certainty, offer all the advantages pointed out above and leave nothing to be desired as to practibility or efficiency:
 l. About OF. of the finely pulver- ized ore is placed in bottle, an equal volume of tincture of iodine is added, and the mixture agitated. The con- tents of the bottle are kept in contact for an hour at most, with occasional agitation, and finally allowed to settle. A strip of Swedish filter paper is then introduced into the clear solution and dried, these two operations being re- peated six times, so as to saturate the paper thoroughly. The strip is then burnt, when the ash, in case gold is present, will show a purple coloration, which on pouring brOmine water over it will quickly disappear.-a sure indi- cation of the presence of gold. This operation is best performed on a plate.
 ?. The test for gold described above may be altered in the following man. her: About 4 oz. of the finely divided ore is covered with an equal volume of bromine water in the same manner as above. After standing and agitating for an hour, the solution is filtered and tin chloride solution added to the ttl- trate to produce the purple of Cassius, the appearance of which will indicate the presence of gold.
 The methods given are especially adapted for the separation of gold sul- phides. It is necessary. however, in this case to roast the suIphides before the application of the process; an opera tion which can be readily accomplished in a can or pan over the camp fire. When roasting pyrites for this purpose the temperature towards the end should be raised to full red heat, so as to in duce complete decomposition and ren- der the product porous and readily permeable for the iodine or bromide solutions. If the ores to be treated con- tain all excess of carbonate of lime, the roasted mineral should be gently re- ignited with ammonium carbonate, so as to prevent the entry of much lime into the iodine OrbrOmide preparations.
 To execute the tests described above there would be required a few empty bottles, bottle of iodine tinCture, an- other of brOmine water, another con- taining a solution of StannOus chloride, a couple of glass tunnels, some filter paper and some ammonium carbonate, surely list that cannot be surpassed in simplicity, cheapness and adaptibil- ity.-Dr. J. H. Only, ill Engineering and Mining Journal.
 SUMMONS BY PUBLICATION.