C—l2a

12

(3.) More efficient methods are required of separating the gum from bhe large amount of dirt and foreign matter in the crude product obtained in the first treatment of the ewamp material by the various washing plants. The process of drying and winnowing universally employed ou the field is both wasteful and incomplete, as much of the lighter gum is lost and a, very large proportion of dirt and foreign matter is retained. More complete separation could probably be effected by water treatment of the wet product before drying. Much of the gum will float on water, and could be removed in a, comparatively pure condition. The residue, containing only the dense) , and harder gum, could, after drying and further washing, be much more effectively winnowed than the original material. The most efficient practicable method that has so far been evolved lor the removal of foreign matter associated with gum is the Maclaurin process. This process is based on the faot thai, almost all the foreign matter, when Creed from air in a, vacuum, will sink in brine of specific gravity .'!() (Twaddell). whereas the gum will float. The process, which has been fully described in C-12, 1918, page 9, has been in operation on an industrial scale in the Government kauri-gum store in Auckland for two years, and has proved very successful. It is desirable, however, that the commercial efficiency of the process in the treatment of the wet product obtained by the first treatment of the swamp material should be investigated. If the wet product can be profitably treated in this way on the field, the lengthy process of drying and winnowing will be eliminated. It may, however, be found profitable first to remove the lighter gum by flotation on water, as suggested above, and to remove more of the dirt from the residue by washing. Industrial experiments carried out- in the first instance in Auckland, making use of the plant installed at the Government kauri-gum stores, would indicate whether the process would he likel\ t;> lie satisfactory if carried out on the field. If encouraging results were obtained, an experimental industrial plant should be installed on one of the guinlields. preferably at Mangawai or Waiharara, where sea-water could be used as a source of brine. We are of opinion thai the Maclaurin process should be made more easily available to private companies, the present royalty being too high and considerably in excess of that payable by the Government. We recommend that in the event of the process being purchased by the Government it should be made available to private individuals and companies either free or on the payment of a very small royalty. (4.) In order to encourage private enterprise and investigation, bonuses should be offered for improvements and inventions in connection with the kauri-gum industry. We suggest that for this purpose ,i sum of not less than £5,000 be- set aside, to be allocated in various amounts as rewards for such investigations and improvements as shall have proved to be of material advantage to the industry. Although more than half of the gum-bearing lands belong to the Crown, all the investigations hitherto made have been carried out by private individuals and companies. It is desirable that the Government should in every way encourage such investigation in the interests of the industry, and should also be prepared to make investigations in connection with the extraction of gum from Crown lands. In addition to the kauri-gum dug from the soil, an appreciable amount of gum is obtained from the living kauri-tree by the process known as " bleeding."' or " tapping." This recent gum, however, differs in many respects from the fossil gum. Many years ago indiscriminating hacking and bleeding of the kauri-trees was permitted, both in the State and privately owned forests, without restriction or control, and as a consequence much injury was done to the trees. When this was realized the practice was put an end to as far as the State forests were concerned, but bleeding was continued and is still carried on in private kauri forests. The