Other essential oils may be obtained by distillation, water being added to the ingredients in sufficient quantity. In this manner, they are drawn from the various parts of plants which yield this substance, whether flowers, leaves, barks, roots, or woods, or from their extracts, in the form of gums or balsams.

The use of these oils to the perfumer is too well known to require explanation. Some of them are also employed in pharmacy and chemistry, others in confectionary.

But there are oils which partake of the nature of those named essential, which are of greater utility, and more extensive application. These are called empyreumatic oils, and are obtained by dry distillation.

Birch oil is classed among these; it is prepared by the Tartars from the white bark of the birch-tree; and, what is singular, that which is extracted from bark in a rotten state, is esteemed the most valuable. It is used in the preparation of leather, for which purpose it is in great request, on account of its antiseptic qualities.

But a far more important extract, of an empyreumatic nature, is the tar, so extensively used for naval purposes. It is distilled from the wood of the fir-tree, and produced in large quantities in the north of Europe, and in North America. In the selection of the wood for this purpose, some care is taken, as particular trees yield much more tar than others. When a sufficient quantity is collected, a circle is marked out on the ground for the kiln. The earth is then dug out, a spade deep, sloping from the centre to the circumference, and is thrown up, forming a bank round the circle. A straight pine, of sufficient length to reach from the centre some way beyond the bank, is split longitudinally, and hollowed out. The parts are then put together again, and one end is placed in the centre, being so supported on the ground, that this end is higher than that which comes without the bank, where a

of Moringa aptera, a leguminous plant, nearly related to our honeylocust, to the logwood, and other trees of that character. The oil is used not only by the perfumer, as stated in the text, but by the watchmaker, as a portion of it, which separates on standing, is not liable to congelation.-AM. ED.]

hole is dug in the ground, into which the tar flows from the channel, and whence it is from time to time taken out and barrelled for market, without any further preparation.

In packing the billets of wood in the kiln, the inward ends are made to slope towards the middle, which is filled up with smaller pieces, consisting of knots of wood, the most productive part of the trees. After the whole billets are piled about twelve or fourteen feet high, a number of small logs are placed round it, then a layer of turf, and so on alternately throughout the whole height. The top is then covered over with two or three layers of turf. The fire is at length let in at the top, by removing the turf in ten or twelve different places; and the pile burns slowly downwards till the whole of the tar is distilled from it. Six or eight days are generally required to complete the burning of a tar-kiln of the dimensions here described.

The above is the common method pursued in the north of Europe; but though unexpensive, it is attended with great counterbalancing inconveniences. Among these the chief are, that the management of the fire is extremely difficult, and considerable loss takes place in extracting the tar. Other methods are, therefore, resorted to by persons possessing capital, which I must not stop to detail.

The quantity of tar retained for home consumption in 1830, was 5205 lasts.

Pitch, which is condensed tar, is obtained either by evaporation or burning. The process of burning is performed very simply. A hole is dug in the ground, and lined with brick. It is then filled with tar, which is ignited, and allowed to burn till the pitch is found to be of sufficient consistency, which is ascertained by dipping a stick in it, and allowing the pitch adhering to it to cool. When the tar is sufficiently burnt, the hole is covered up, and the fire is thus extinguished.

When tar is converted into pitch in this country, a much more economical plan is pursued in the large establishments. Here no part of the tar which has any useful property is wasted. It is evaporated in a still, and con

sequently the valuable volatile products are condensed and preserved. The oil, the acid, and the water, which distil over, do not mix, and may be easily separated by further distillation. The oil is an inferior oil of turpentine, which is useful in coarse painting; the acid is strong and empyreumatic, very closely resembling the pyroligneous acid obtained from the distillation of wood. By this method, 600 gallons, or 20 barrels of tar, will produce 10 barrels, or 2200 weight of pitch, 176 gallons of oil, and about 40 gallons of acid.

Besides the British made pitch, 5482 cwt. of foreign pitch were retained in 1830, for home consumption.*

FOURTH WEEK-SATURDAY.

TREES TALLOW AND WAX.

THERE is yet another class of substances derived from some kinds of trees, which I shall describe on account of their singularity as vegetable products, and the uses which be made of them both for domestic purposes may and in the arts; I allude to such as bear a close resemblance to tallow and wax, both of which are but little practically known, in our temperate climates, except as the produce of animal secretion.†

* [England is the great customer of the United States in this article. In the year 1837, there were exported to that country, 19,634 barrels of tar and pitch, and 198, 294 barrels of rosin and turpentine, valued altogether at 733,065 dollars. To all other parts of the world there was exported an additional quantity, valued only at about 90,000 dollars more.-AM. ED.]

† Bees-wax was long believed to be collected by these industrious insects from flowers; but it is now satisfactorily ascertained that they secrete it through the rings of their body. Wax, however, is not altogether unknown, even in this climate, as a vegetable production. The experiments of Proust led him to believe, that the bloom which silvers the surface of plums, and other stone fruits, is wax, and that the property of resisting moisture, which resides in the leaves of the cabbage, and some other plants, is owing to the presence of the same substance. Some trees, too, such as the poplar and alder, afford a decoction resem

A substance very nearly similar to tallow is procured from a tree growing abundantly in China, called the tallow-tree, or Croton sebiferum,* which is used by the inhabitants in making candles.

Mr. Clark Abel describes it as being one of the largest, the most beautiful, and the most widely diffused of the plants found by him in China. "We often saw it," he

says, "imitating the oak in the height of its stem, and the spread of its branches. Its foliage has the green and lustre of the laurel. Its small flowers, of a yellow color, are borne at the end of its terminal branches. Clusters of dark-colored seed-vessels succeed them in autumn, and when matured, burst asunder, and disclose seeds of a delicate whiteness."†

The seed-vessels are hard brownish husks, not unlike those of chestnuts; and each of them contains three round delicately white kernels, resembling in size and shape our ordinary hazel-nuts, but having small stones in the interior. It is the hard white oleaginous substance surrounding these stones which is used as tallow, and possesses most of its properties, though its consistency is so great, that in stripping it off, it does not soil the fingers. From the shell and stone, oil is extracted, so that the fruit produces tallow for candles, and oil for lamps.

The tallow thus procured is not so cohesive as that produced from the fat of animals, and to remedy this defect, the candles are dipped in wax. Father d'Incarville, in a letter published in the Philosophical Transactions in 1753, states, that almost all the candles sold in the southern provinces of China, are made with tallow prepared from these berries. There are few sheep in that part of the country, which causes animal tallow to be very scarce, and enhances the value of this vegetable production.

bling wax or tallow. As for the latter substance, it is nearly akin to the oils which are not uncommon in the vegetable productions of temperate climates.

* [Now called Stillingia sebifera. This genus and the proper crotons stand near to each other in the euphorbiaceous order of plants.— AM. ED.]

+ Travels in China, p. 177.

The piney tree, or Vateria Indica,* growing on the coast of Malabar, yields a substance of the same kind as that already mentioned. The peculiar product of this tree, is described in an interesting paper, by Dr. Benjamin Babington, published in the Quarterly Journal of Science. He has shown, from many experiments, that its inflammable properties admirably adapt it for the manufacture of candles, and, indeed, that it is in every way superior to animal tallow. This useful substance is obtained from the pulpy fruit, by simply boiling it in water, when it rises to the surface, and, on cooling, forms a solid cake.

The natives do not make use of the substance for light, candles being unknown among them, as the country furnishes many fluid vegetable oils, with which they feed the wick of their lamps; but they employ it medicinally, considering it an excellent application for bruises or rheumatic pains.

A resin very similar in its properties to that of copal, exudes from the piney tree, and furnishes a very durable natural varnish. This resin, when mixed up with the tallow of the tree, is used as a substitute for tar, in smearing the bottoms of boats.

The produce of the piney tree might form a useful and profitable article of commerce. It grows abundantly along the western coast of the Peninsula of India, as far northward as the extreme limit of the province of Canara.

Wax is produced from a species of palm, which grows in the Brazils, and rises to the height of thirty feet, called by the inhabitants Carnauba. The lowlands on the banks of some of the rivers are covered with these trees. The leaves are two feet in length, and, while young, are folded in the manner of a fan: when they afterwards expand, they are nearly two feet in breadth. When cut from the tree, as soon as they have reached their full growth, and placed to dry in the shade, a considerable quantity of

Its

* [Formerly called Eleocarpus copalliferus. The tree is associated in its natural character with the Tiliacea, lime or linden trees. resin is commonly called Indian copal.—AM. ED.]