Frequently a third small box, 0,80 m. long, 0,54 m. broad and 0,25 m. high is placed on top of the upper one. This box is also open on the lower side, standing in water 10 cm. deep. The sides likewise project over the top so that a layer of water 5 cm. high remains on it. The vapors from the last chamber (fig. 40, h) of the large condenser pass through a tube (fig. 40, k) into this smaller box where more camphor is condensed. This upper condenser is provided with a small exit tube for the vapors.
The following utensils are used in connection with this apparatus: a wooden shovel of the shape of a spoon-oar for shovelling the distilled chips into the fire place; also an iron poker. In order to protect the stove and tub, a roof of straw and reed is constructed, also a screen of straw matting to the windward (valley) to protect against draught and rain.
The production of camphor is conducted as follows. After the pan has been filled with water, the chips are introduced through the upper opening into the tub, and all cracks and crevices carefully luted, so that the vapors cannot escape. Only a moderate fire is maintained. In the course of the distillation the pan is frequently refilled with water through the tube c (fig. 40). The vapors pass through the perforation into the tub (fig. 40,</) and convey the camphor vapors from the heated chips through the bamboo tube (fig. 40/) into the condenser where they are deposited. In the early part of the distillation, camphor oil only is found in the condenser, later, also solid camphor. Most of the camphor condenses behind the 3rd, 4th and 5th partition of the seven-part condenser. The tub holds 112,5 kg. of chips, a quantity that can be distilled in 24 hours. The exhausted chips are removed from the lateral opening (fig. 40e). Every week the condenser is opened; and the camphor and the camphor oil contained therein, removed.
On the surface of the water in the condenser there collects a granular crystalline mass resembling a mixture of snow and ice, which at least in the first chambers is mixed with camphor oil and is colored yellow. On the walls of the condensing chambers not standing under water and on the cover of the box pure, white crystalline camphor is deposited. The yellowish or brownish-black camphor oil floats on the surface, where it mixes with the granular camphor.
This type of distilling apparatus appears to have given satisfaction under the conditions under which it is used. At all events it is much better than the old Chinese equipment which was formerly universally in use in Formosa and which, since the Japanese occupation of the island, is disappearing more and more, being displaced by Japanese apparatus. The accompanying description of the Chinese plant, also the illustration (fig. 42) are taken from the book by Davidson1) already referred to.
A rough shed is constructed to cover the plant, which, if of the usual capacity of ten stills, measures about 2,1 x 3 m. Such an equipment is termed "stove." The ground is beaten down, so as to afford a firm foundation. Four planks are now formed into a bottomless box-like frame 18 inches high. This frame is filled with earth which is stamped down hard and allowed to dry and form what might be called the foundation of the stove. Ten round holes (A fig. 42), less than a foot apart, are now cut out on each side of this base, each shaped so as to support a circular iron pan (B) 38 cm. in diameter which is intended to hold water. There is no chimney. The smoke is expected to find its way out through the opening through which the wood used as fuel is introduced. After the pan has been covered with a perforated board, a cylinder (C), or rather a truncated cone made of staves and known as a "still" is fastened to this base by means of a mud paste. This still is 0,5 m. high, its lower diameter is 0,3 m., the upper diameter 0,17 m. Two large planks are now placed lengthwise of the structure reaching as high as the retorts. The place thus enclosed is packed full of earth and pounded down hard, thus preventing the retorts from being cooled. Above the retorts are placed inverted earthenware pots (D), 0,43 m. high and 0,35 m. in diameter, in which the camphor collects. This completes the outfit.
1) Comp. footnote 1 on p. 448.
Fig. 42. Chinese still, such as was formerly used in Formosa.
As a rule a man and his family attend to such a still. Both morning and at noon he goes into the forest with basket and axe for the purpose of getting camphor chips from a special tree, which is generally not further than 1,5 km. from the still. After three hours he returns with about 36 kg. of chips 7 to 10 cm. long. Before putting them into the still they are comminuted still farther. This is usually done with a wooden club serrated on the side used. A single charge consists of 5,5 to 6 kg. of chips.
After the pans have been filled with water, the fires are lit, and are allowed to burn slowly during the entire night. The next morning the chips are taken out, the lower half thrown away and the upper half, together with a sufficient quantity of new chips, put into each retort, the partly exhausted chips being placed at the bottom. Twice daily the charge is changed. The water vapors which pass slowly through the chips carry with them the camphor vapors which condense in the earthenware pots. After 10 days the pots are taken off and the camphor, which has sublimed to a snow-white mass, is removed. The amount of camphor that has accumulated in each pot varies between 2,5 and 4 kg.