KAURI GUM

Dominion, Volume 11, Issue 43, 14 November 1917, Page 9

KAURI GUM

A NEW CLEANING PROCESS

IMPORTANT INVENTION BY DOMINION ANALYST,

For some little time since the Government has been interested in the S an l3 gum industry as a buyer of gum, [",4 Dominion Analyst (Dr. MacLaurin) das bean experimenting with methods of cleaning gum, an operation which ass np till the present been one of great' difficulty. Failure to discover an efficiont method of petting rid of dirt from the gum has probabzly cost this country hundreds of thousands of pounds. Dr. •MacL'aurm has at length hit upon a scheme-b ? which it will be possible to treat considerable quantities of gum, and to clear it of all but an inconsiderable residue of dirt. Most peoplo know that kauri gum is a_-resin, and. thoy have perhaps seen pieces of it on exhibition which have tne appearance of high-grade amber-col-oured resin. But in actual working very little of the guirt is found in this condition. It is more often found in small Pieces, ranging from the size of a fairly largo pea to that of a turnip seed, and mixed with it there may be from 25 to SO per cent, of dirt. From gum of this class it has hitherto not been possible to extract the impurities by any payable method. Dr. MacLaurin has set himself to the task of treating this class ■ rW and te has nt len S tlv devised a method and a contrivance by which it will be possible to treat gum at moderate cost. v The commodity in pure state IS of very high value, and the treatment of it by this cleaning process in this country prill vary much enhance ite value. , The first part of the operation is to immerse the gum mixed as it is with dirt in a 6trong solution of common salt. Apparently the salt has no other part in the process than to increase ilia specific gravity of the liquid, and so to increase its floating power. The idea of the operation is that the gum will float in the solution, an<i that the dirt will sink. What actually nappens when the gum is immersed is that thu whole mixture, except a small portion of tie heaviest of the dirt, floats. The dirt is really of higher specific gravity than the solution, and it ouglit therefore-to sink. It Boats because it is porous, and is full of tiny bubbles of air. Experiment has .shown that even if left to stand for a long time the bubbles do not wholly disappear and the dirt :e----■mains mixed with the gum. The problem of getting rid of the air is solved by sealing up the mixture in an airtight cylinder or. other vessel, and by means of an air pump creating « vacuum in it. By this means the air. is extracted from ;the interstices of the dirt, and .-ffib dirt .sinks,- leaving the gum floating clean on the top of the solution, jo remove the clean gum is then a ample operation. Even the solution need not bo lost. The <iirt may bo filtered out of it, and the brine used over again. The process discovered by Dr. MacLaurin is likely to prove one of great valne to the gum industry, and it ;'s sure to be extensively, used when the gum. trade is resumed after the war.