THE MANUFACTURE OF POTASH

Evening Post, Volume XCIII, Issue 48, 24 February 1917, Page 9

THE MANUFACTURE OF POTASH

TO TUS EDITOR. Sir, —It is interesting to know that some of our younger scientific men are endeavouring to benefit the country they are living in, by trying to wrest from Nature some of her secrets. ' Mr. B. C. Aston, chemist to the Agricultural Department, is now engaged in an endeavour to obtain supplies of potash from materials in this country. In a short account Which appeared <in the Evening Post of the 19th instant, as to what he and some others have been doing, mention is. made of a mineral called Felspar, which occurs in granite and schist, schist forming a considerable portion of the interior of Otago. ■ It is from this schistose rock that most of the gold found in Otago has been : derived. Associated with the gold in the quartz is scheelite, now a most valuable product. Before the war the value was about £16 per ton ; now it is £200. The' use is to harden steel.

Schist also occurs at Top Valley and Wakamarina in the Marlborough Province. There also scheelite is found with gold in the quartz reefs. It also forms one of the chief formations at Chatham Islands, but neither gold nor scheelite is found in it. I am afraid, however, that the cost of extracting the potash from this rock will be too much, as the rock will have to be crushed. The only water power available is the Kawaru River, and it is doubtful whether the amount of potash obtained would recoup the cost. As to utilising the seaweeds on the New Zealand coast, and particularly the kelp, which is found chiefly on the coast of the southern islands, the difficulty of getting at them on account of the rough coast line would prevent vessels from collecting it, besides the cost of necessary furnaces and fuel.

The suggestion of the burning of the sawdust which has accumulated at the various mills for the 'potash it contains is not likely to be a success. In the first and chief place, the quantity of sawdust at any one mill is not enough to make it worth while to erect the necessary furnace, as sawdust is most difficult to burn. The quantity of potash in some of the native forest trees is small. Rimu, which forms most of the timber cut, at all events south of the kauri line, I am informed, is poor in potash, having the. lowest percentage. Rata, however, is said to contain a high percentage, but unfortunately is not plentiful, and there is jvery little cut at any of the mills. .

There is, however, a chance for the City Council to make revenue, and reduce the rates. This knowledge some of the- councillors may have concealed! When the vote came on for the extermination of the gorse on the Town Belt they voted-against it, so the destruction \vas,,not proceeded with. Gorse contains a very high percentage of potash. This is proved by the" way it conies up .after being cut down and burnt, and it does not require special cultivation.

As for the extracting of potash from alunite, this mineral is only found at Rotorua, being deposited by geyser action ; it can be put aside.

Regarding the} suggestion of Mr. Parry as to obtaining nitric acid by means o£ electricity, I call attention to an article in the Dominion of ,25th November, 1916, written from information given by Mr. Orchiston, Chief Telegraph Engineer, which r no doubt will receive the attention it deserves, when the war is over,.'as in.'the localities, mentioned there is everything needed except the furnaces, piping, and wire.— l am, etc., HENRY H..TRAVERS. 22nd February.