IMPORTANT DISCOVERY NEAR ROTORUA.

New Zealand Herald, Volume XXII, Issue 7405, 13 August 1885, Page 6

IMPORTANT DISCOVERY NEAR ROTORUA.

Da. Gindkks, the medical officer In oharge the Rotorua Sanatorium, publishes in the Hot Lakes Chronicle the' following letter — "Sir, —You are aware that at about a mile from the new township of Rotorua there are two we ird and desolate looking spots, one on either side of the Wairoa-road, known as Sodom and Gomorrah. Which is Sodom and which Gomorrah is a point not yet determined ; the visitor may take his choice, aud have nothing to pay for the privilege. Turning into the barren region on the right,which we will, if you have no objection, call Sodom, a wide sulphur covered plain is discovered, where tons of the mineral lie patiently waiting for the hand of man to convert it to use and profit. This must have been at one time a scene of the wildest plutonic activity ; but now all is desolate and dead. Proceeding further we descend into a veritable valley of Hinnom, at the bottom of which is a lake, with its waters black as Erebus and silent as the grave. No sound breaks its unruffled calm save ever and anon the bursting of a lazy bubble ou its surface. This pool is an ancient burial place of the Maoris, and generations of the dusky race lie hidden beneath its dark waters. My object, however, sir, is not so much to direot attention to the poetical as to the practical and profitable aspects of this neighbourhood. Not only is there sulphur enough here to keep large acid works going for years, but we have discovered a valuable deposit of diatomaceous earth. It is a creamcoloured, homogeneous-looking solid, which when pressed in the hand takes a clay or putty-like consistence at first; but if still further manipulated with a little agitation, becomes fluid and streams away through the fingers. A mass weighing 19 ounces, when perfectly dry weighed only 7 ounces, so that I it is capable of absorbing more than twice its own weight of water. It specific gravity is '666 ; white like chalk, in fact it may be regarded as a fresh water chalk, for just as the marine infusoria have employed carbonate of lime for their covering, these fresh water diatoms have used silica. A few grains of the dry powder, in a drop of water under the microscope, reveal many of the well known diatomaceous forms, the most abundant being those of the tetracyclus lacustriß, tabellaria, and cymbella. The commercial value of this substance consists in the fact that it is essential to the manufacture of dynamite, which consists of earthy matter saturated with the explosive compound known as nitro glycerine. The more of this substance the earth is capable of absorbing the more valuable it is for the purpose. As far as I know there is only one place in Great Britain where an earth suitable for this purpose can be obtained, and that is at Ardrossan, in Scotland. It is valuable also as a polishing powder for metals, indeed for cleansing silver I know of nothing equal to it. It is probable that the electroplaters of Birmingham and Sheffield would appreciate it highly. I am aware that deposits of similar infusorial earth exist elsewhere, notably at Tikitere and in the Taupo district, but I have not yet met with any equal to that from Sodom in its absorbent power and low specific gravity. The discovery of this material has excited a good deal of interest here, and specimen collectors have been numerous and busy. The Government, who in the future may hope to derive considerable revenue from these deposits, are not liMy to offer any objection to visitors possess. themselves of such specimens ; but if 1 am not mistaken, they will regard with some suspicion any attempt to carry away quantities exceeding the limits of a fair sample. Verbum satis sapienti.— Alfred Gindkrs. Kotorua Government Laboratory,Rotorua, August 3, 1885."