84

C.—4

The process of extraction is simple and inexpensive. All parts of the plant, including the leaves, are burnt in dry pits dug in the earth from 3 ft. to 5 ft. in depth, and of any convenient size. The ashes are placed in tubs or vats, p each having an orifice near the bottom secured by a plug, and a false bottom covered with straw or rushes. The ashes are saturated with water, and after standing about twelve hours the potash-liquor is drawn offhand taken to the evaporating-pans, usually shallow iron vessels, sometimes with corrugated-iron bottoms. It is now kept in a boiling condition and constantly stirred, fresh liquor being added from time to time as required until the whole becomes of a pasty consistence, when the heat is gradually reduced and the dry residuum allowed to cool. The crude potash thus obtained requires to undergo a process of calcination to free it from certain organic matter before it becomes the potash of commerce. Charcoal. i I • There is always a certain demand for this product, which requires great care and attention in manufacture, though the ordinary process is extremely simple. Particulars as to the manufacture are readily obtainable. Bark. Large quantities of the bark of the kamai, tawhero, and tooth-leaved beech were used by local tanners in past years ; but since the importation of mimosa-back from Australia the use of indigenous barks has been neglected. The bark of the tanekaha was discovered to possess a special value as an organic mordant in the preparation of basils, and at one time realised from £30 to £50 per ton in London. _ Both the hinau and rata afford tanning-bark of high-value, and it may be fairly assumed that bark yielding from 18 to 22 per cent, of tannin would realise £6 per ton at the local tanyards. Settlers clearing their land would find it profitable to peel these trees after felling, and sell the bark to the nearest tanner. Rimu-bark only contains 4 per cent, of tannin, and is practically valueless. The same difficulty in a reduced degree occurs with regard to beech, containing 7 per cent, of tannin ; pokaka, 9 per cent. ; and kamai, 12 per cent. ; although the latter might compete successfully with wattle. In the United States extract of hemlock is made from bark containing only 9 per cent, of tannin, so that it is evident that much of our local trees could be utilised in some such manner.