JAPAN
The lac is obtained from a variety of the sumach, called in Japan urushi-no-ki (Rhus vernicifera). A horizontal incision is made in the trunk of the tree, and in a few minutes this channel becomes filled with a greyish-white emulsion which, on exposure to the air, changes to light brown and ultimately to black. This juice may be taken from the tree at any time from April to October, but midsummer is the best season. The yield of one tree varies from twenty-seven to fifty-four grammes, and to obtain that quantity it is necessary to destroy the tree. It appears from official figures that at least a million trees must be sacrificed annually to the needs of the manufacturer, and readers will not be surprised to learn that of late years a demand has arisen for Chinese lac, which, since it can be sold in Japan at a lower price than that of the domestic product, is used for inferior classes of work. According to analyses made by Korschelt and Rein, the substance thus obtained from the lacquer-tree contains from 60 to 85 per cent of lac acid (C14H18O2); from 3 to 6% per cent of gum arabic; from 1.7 to 3.5 per cent of albumen; and from 10 to 34 per cent of water. To prepare it for use, it is first pressed through cotton-cloth to remove extraneous bodies,—as bits of bark, wood, etc.; it is then ground in a wooden tub for the purpose of crushing the grain and obtaining uniform liquidity; subsequently it is again strained, and finally the water it contains is expelled by exposure to the sun's rays or to artificial heat.[1] While the drying process is going on, various ingredients are added according to the kind of lacquer to be produced,—gamboge for nashi-ji (pear-ground) lacquer; perilla oil and plum-juice for
- ↑ See Appendix, note 60.
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