1G3 



SECTION D. 

 MINOR FOREST PRODUCTS 



Tannins. 



While tannin-bearing products are very common in 

 the forests of the Islands, the largest source of this 

 important commodity is in the mangrove forests. A 



recent analysis of the barks 

 species found in these association 



of 



the three principal 

 . which was made 



by the Forests Products Laboratory — a department of 

 the Commonwealth Institute of Science and Industry 



^ave 



tin; following results: 



Species. 



Tans. 



Xo. 212, Bruguiera 



Rheedii 

 No. 213, Rhyzophora 



nvucrcmata 



No. 343, Xylocarpus 

 granatum 



31-0 



18 



24 1 



Non- 

 tans. 



11-2 



6-8 



16-1 



Tn- 



dolubles. 



46-8 



63 • 4 



48-7 



Metis 



tu IV, 



Colour on a 5 

 per cent. 



Solution. 



11-0 



11-8 



Reds. 



Yellow 



11-7 



11-1 



13-5 



9 • 5 



23-2 



30-0 



17*8 



The percentage of tannin is satisfactory, and com- 

 pares favorably with results obtained from barks of 

 the same species gathered elsewhere in the tropics. 

 As they had a long journey to make before reaching 

 the laboratory, it is probable that some fermentation 

 had taken place, and this has always the effect of 

 lowering the tannin content. It is quite possible that 

 fresh barks, examined in Papua, would yield still 

 higher results. How serious is the trouble of fer- 

 mentation is shown by the analysis of equal quanti- 

 ties of the barks taken at the same time from the same 

 trees, but which were, instead of sun-dried, partially 

 dried in the water-jacket ted drier. The idea of so 

 drying them out was suggested to me by the officer-in - 

 charge of the Forests Products Laboratory, the object 

 being to dry so quickly as to prevent any enzymic 



action, which not only destroys the tannins, but pro- 

 duces colour. 



carried sufficiently far, 



Unfortunately, my drying was not 



and the partially dried 

 material, sealed in tins, was in an ideal condition for 



been responsible for a dispersion, different in 

 degree from the sun-dried sample. This disper- 

 sion would seem to have been protected by the 

 presence of this saponaceous body. It looks as 



though a selective absorption of this saponaceous 



body has occurred, resulting in varying the pep- 

 tisation of the dispersion by water. The par- 

 ticles, then, pass quite easily through the filter 

 papers used, with the object of filtering the solu- 

 tion optically clear for examination in the Lovi- 

 bond Tintometer." 



The red colour trouble with 



mangrove 



bark is a 

 very serious one, and has prevented its use to a great 

 extent. Any means that will reduce this colour are 

 to be welcomed, and among them the obvious one is 

 to treat the bark on the spot, instead of exporting the 

 raw bark as has so often been done, and which has 

 resulted in financial loss. The price of the bark is 



that the 

 bark cannot be profitably stripped and exported. That 

 it can be treated locally, and the extract exported 

 profitably, is shown by the Borneo experience, where 4 

 extract works are operating. These are often called 



so low, and shipping freights are so high, 



ditching mills, 



mane-rove 



bark euteh having super- 



in (urn, was super- 



seded the Indian acacia dye. It 



seded by the aniline dye, so that to-day mangrove 



cutching mills turn out tannin extract. 



The chemical reduction of the objectionable colour- 

 ing matter is a problem still awaiting satisfactory solu- 

 tion. Queensland is also interested in the tan bark 

 of her mangrove swamps, and a committee was ap- 

 pointed under the Institute of Science and Industry 

 to investigate the question of decolouration. The 



i wo barks dealt with were li . Rheedii and //. muc- 



ronata. This committee succeeded in preparing a good 

 blown leather, lighter in shade than the ordinary red 

 of mangrove-tanned leather, but not a light-coloured 

 leather. 



such as wattle tannage produces. Nor 



was 



it able entirely to eliminate the smell which is mother 

 objection to mangrove leather. The process did not 

 alter the colour of the solution used, but the leather 

 produced was lighter in colour. Work was also done 

 by the Forests Products Laboratory of the Institute 



No. 212, B. Rheedii: 

 °3.5 yellows. 



°/c 



the enzvms to act; and they did, with the result that . iii -• , ^ 



all the alleged oven-dried material, instead of showing of Science and Industry on the decolouration of the 



less colour and more tannin, showed the reverse. Here tannage derived from the man gum (Eucalyptus 



are the data* caJophyUa) of Western Australia, and possibly the pro- 



, , cess used in that case might help with mangrove tan- 



reds and & L ° 



nage. 



Failing a chemical correction, the best thing seen 

 to be to extract the tannin as soon after cutting the 

 bark as possible, which means the establishment of 



extract works at the place where a large supply exists. 



from in the Mandated Territory the areas of mangrove are 



small, but in the Territory of Papua they are vwy 



No one, who has travelled from the 



Xo. 213, R. mucronata: 14.5% tannin; 11.7 reds 



and 25.6 yellows. 



Xo. 343 ? X. granatum: 16.4% tannin. 



c 



from 



ha 



The experiment of sending oven-dried bark 

 Papua to the Perth laboratory, though a failure 

 l he point of view of obtaining optimum result t 

 at any rate proved quite definitely that fermentation 

 has the effect of destroying the tannin, and increases 

 the objectionable red colour. This theory has been 

 held for some time, bur I think the experience just 

 quoted places the matter beyond further argument. 



That no colour data is furnished in regard to No. 

 343 is due to the sanonaceous body that the bark 



large indeed. 



Alele mouth of the Purari delta right through to 



Kikori 



will have failed to appreciate this, for the 



in a dense mass of n i au- 



la rge 



mangrove formal ions on 



tl 



le 



IS 



contained. 



saponaceous vw.ij 

 I will quote the explanation of the ofiicer- 

 in-charge of the Forests Products Laboratory, Mr, D. 

 (oghill, in full: 



"It would appear 

 changes, which have occurred in this sample, have 



t hat the fermentation 



waterways are white ribbons 



grove forests. This area, though large, is, I am told, 



exceeded by the 



tidal reaches of the Omati. Turama, Bamu and Fly 



rivers. Galley Reach, too, offers a very large supply 

 of mangrove indeed, and there are doubtless many other 

 mangrove swamps of that type that I have not 

 had the opportunity of seeing. The bark of the first 

 two mangroves runs about 9 tons to the acre. With 

 the great increase of the use of tanning extract for 



