TOWAI BARK.

Taranaki Herald, Volume XVI, Issue 821, 18 April 1868, Page 3

TOWAI BARK.

To tlie Editor of the Taranaki Herald.

Sir, — A few months ago yon made some remarks on a samplo of an extract manufactured from the Towai. Sinoe that samples have been forwarded both to Wellington aud England, j Throngh the coartesy of Dr. Heotor and Mr. Skey, I have been favoured/with a copy of the ! result of an analysis which was made in the laboratory attached to the New Zealand Geological Survey department. Tho sample forwarded to England, has been sent to the well known Analysist, Professor Herapath, of Bristol, his results have not yet arrived. In all probability the latter will show a greater amount of taunic acid than is given iv Mr. Skey's report ; this is owing to the difference in the bark from which the extract was made ; the Wellington specimen beitig made from bark that had been stripped in autumn, and suffered to remain in the bush, exposed for the whole season to tbe iuclernent weather of winter. That on tho contrary which was sent to England, was made from recent bark stripped •early in the spring. Tannio aoid, from itssusoeptibility of change in color when exposed to tho action of light, is largely used for photographic purposes. This peculiarity offers a good test as to the richness of the bark in tannic acid. The person engaged in stripping, will observe in the spring wheu the sap has ascended and tho bud is bursting forth, that the surface of the tree when deprived of its covering will quickly pass through a variety of beautiful tints. As the season advances, notwithstanding that the bark strips with equal facility, these changes lake a far longer time. From this fact we may arrive at the conclusion that the bark is best suited for oxtraot mauufaoturing or tanning purposes in the spring when tho sap is ascending with vigour to nourish the yonng shoots, and form the seeds.

In the analytical report, 425 of catcchuic acid and 31*1 of tannio acid is given ; it is these two that form — when combined with the gelatine of tl c hide — leather. Catochuic acid is known as mimotannio acid. Berselius has termed it thus in order to make a distinction from tho aoid produced by the onk. For tho tanner a siinplo tost may bo easily extemporised, by which the valuo of tho extraot can bo arrived at. Let 100 grains of gelatine be dissolved in a sufficiency of hot water to render tho solution quitq^iqnid, to half of the quantity let some of the tan liquor generally in use bo added until a precipitate ceases to foil. To the second half weigh, let us say, five grains of the extract, and dissolvo in water, and then by experiment test as to tho quantity of golatine it will throw down . By this simple means a comparative value may bo quickly and truthfully arrived at ; common glue maybe used in placo of tho refined gelatine. There is one" feature in connection with tho extraot worthy of the tanner's notice, and that is its ready solubility in cold water. Mr. Skey's result shows 73.G per cent, of active tanning matter ; this by careful manipulation may be increased to nearly 90. Analysis of an Extract prom the Towai Tree manufactured bt Mb. Grayling. Physical Description. — Cleavage — irregular compact — easily crushed ; fracture — generally sub-conchoidal ; lustre, resinous, in thin films, transparent, colour almost black by reflected, and garnet red by transmitted light — powder amber colour. Chemical Reactions. — As received, scarcely at all solublo in ether, although softened, but much more solublo after desiccation. In alcohol 95"1 per cent, is soluble. In warm water 96*9 per cent, disolvos, and in cold water it appears as soluble ; but a strong hot aqueous solution, deposits a small quantity thereof when oooled. The addition of hydrochlorio acid or chloride of ammonium to the aqueous solution, makes a further j precipitate. The solution in either alcohol or I water, is intensely red. The aqueous solution of the substance gives abundant reaction of tannio acid with proper tests. Approximate Analysis . — Water 21-5 Cateohuic acid 42*5 Tanuio acid 31" I Ligniu I*B Gum and undetermined matters ... .... 3*l 100 These resDltsshow that the substance is chemically allied to the Kino of commerce, and that it compares well with them, or with the ordinary catechus, in the yield of tannio acid ; it wonkL^ therefore, no^doubt answer the same purposes asP these gums are applied to. As a component of the bark of tho Towai, it has for many years, been applied to the pupposo of taning leather. W. Skey. December 3, 1867. Note. — The Towai is Weiwinannia Ttacemosa, or Sylvicola, and is an allied tree to that which is supposed to- afford the Gum Kino, so that this sab&ance may be valued at the same rate as Kino. J. Hectob. November 10, 1808. In concluding these remarks I may state thafc the waters of Taranaki from their purity ara particularly suited for manufacturing purposes. If you enqniro you will find that furred tea kettles are rarely to be met with. This is to be attributed not so much to the absence of lime in our soils as to the rapid movement of our mountain streams. The water in its passage to tho sea has not time to become supersaturated with carbouio aoid by remaining for a lengthened period in contact with decaying vegetable matter. It may not be generally known that it is this acid that in depositing lime renders water what is termed hard. This simple fact renders Taranaki a most suitable spot for many manufactories, such as dyeing ; and in cloth works a much less quantity of soap would be found to answer the fuller's purpose.— Yours, &c, W. I. Grayling. Mangorei, March 80, 1868.