COMPARATIVE TESTS OF WHANGAMATA ORES.

New Zealand Herald, Volume XXV, Issue 9241, 19 December 1888, Page 6

COMPARATIVE TESTS OF WHANGAMATA ORES.

TO THK EDITOR. Sir,—At the risk of exhausting your patience, I have again to ask you to allow me space for a reply to George Eraser and Son's letter on the above subject, that appeared in your paper of the Mth mst. Into the arena of personal abuse I refuse to follow Messrs. Eraser ; neither will I accept persons who can write as they have done as competent judges of honourable and gentlemanly conduet, in which capacity they presume to seat themselves. As has been the case with Messrs. Eraser all through this controversy, their letter contains misstatements which must not pass uncontradicted. The first of these is, that I take a wrong way of sampling the ore. Again Messrs. Eraser presume to be judges. They make this statement in evident ignorance of my method, which, let me tell them, is <|iiite a well recognised one, being in use in the principal Customs mills in the United States in preference to that which Messrs. Eraser adopt. With thcjinachinery I use, my method is simpler, and more easily applied than the method of quartering, while beinit quite as accurate, if not more so. It consists in taking at regular intervals from the stream of water charged with ore a certain definite portion, including everything coming from the stamps, coarse sand, line sand, slime, and water, just as they come. This is done by catching every ten minutes the whole of the stream in a box made for the purnose. The box is withdrawn as soon as it is filled with water, no overflow being permitted. The contents are thrown into a vat, the water is allowed to become clear, anil is then siphoned oil". The remainder is evaporated to dryness, and the dried ore is sifted, crushed more finely when necessary, and assayed. There is thus no escape of fine gold and silver in the water, as Messrs. Eraser imagine. As a sample is taken in this way from the whole of the ore after it has been crushed, this method is even more accurate than the method of quartering. There is just one point in it to which objection can justly be taken, and, to forestall Messrs. Eraser's criticism, 1 shall point it out. A small quantity of ore remains always in the stamper box as coarse gravel at the end of the crushing. I have assumed that as this gravel is made up of portions of all the ore that has been crushed, it is of the average value of the whole parcel, except that it contains free gold left in the stamper box. To remove this mercury is put in the box, and the ore is passed over amalgamated copper plates. The "headings' or gravel from the box are ground finely in a berdan, which removes amalgam, free gold, and mercury. The sand ground in the berdan is baled into the settling pits, the berdan not being allowed to overflow. My assumption is that this sand is not more valuable than the rest of the sand that has gone to the settling pits, and I leave it to the verdict of men skilled in such work whether any serious error can arise from assuming this to lie the case. Of course the bullion obtained from the box, plates, and berdan has to be added to the amount shown by the assay above mentioned. Let me now Say a few words with regard to the discrepancy Messrs. Eraser notice in the return of gold from the first parcel of ore treated here. I quite expected that they would try to make capital out of this, and also that they would not do me the justice to say that I had pointed it out myself in my report to the Gold water Company. Messrs. Eraser know perfectly well that errors of two or three pennyweights cannot be avoided in the processes of sampling and assaying. If they do not know it tliey have been either extremely lucky or very careless assayers. Remembering the extraordinary results that they not long ago obtained from parcels of sand not only from Waitoa, but also from surrounding properties, which were free from the suspicion of " salting," I am inclined to suspect both their luck and their care. 1 ask the public not to accept their dictum that my assays were wrong because there was a discrepancy of two or three pennyweights between the assay and the return, but to believe that such small errors are encountered in all tests on a working scale. Any competent assayer and metallurgist will bear me out in this, Messrs. Eraser to the contrary notwithstanding. Messrs. Eraser say that it is strange that I treated only the poor ore, and allowed the rich to go to Auckland. I treated the parcels in the order in which the manager of the Goldwater Company wished me to take them. ■ However, _ I shall leave the manager to be dealt with when he brings forth his report, to which Messrs. Eraser refer. The only reason that I did not wait for this report, before replying to Messrs. Eraser, was that 1 wished the public clearly to understand that the whole question depended upon the relative credibility of Messrs. Eraser and myself, they having reiterated a statement which I deny. There is one way open to the Goldwater Company, who are most concerned in this business, _to test which of us is right. The tailings from the tests made here are still available. Let them have assays made by Mr. Pond or Mr. Von Bernewitz, and they will soon satisfy themselves that I am right, and Messrs. Eraser wrong. I am now done with this controversy, and shall not attempt again to confute the protean misrepresentations of_ Messrs. George Eraser and Son. I have pointed out an easy method of settling the dispute. It lies with the owners of the ore to take it or not, as they like.—l am, &c., A. Montgomery. Thames, School of Mines, 18th December* 18S8. ... ,