The following Table shows the quantity of extractive matter and tan in 100 parts of the several substances:—
| Substances. | In 480, by Davy. | In about 8 oz., by Biggins. | In 100 parts, by Cadet de Gassincourt. |
|---|---|---|---|
| White inner bark of old | 72 | 21 | |
| Do. young oak | 77 | ||
| Do. Spanish chestnut | 63 | 30 | |
| Do. Leicester willow | 79 | ||
| Coloured or middle bark of oak | 19 | ||
| Do. Spanish chestnut | 14 | ||
| Do. Leicester willow | 16 | ||
| Entire bark of oak | 29 | ||
| Do. Spanish chestnut | 21 | ||
| Do. Leicester willow | 33 | 109 | |
| Do. Elm | 13 | 28 | |
| Do. Common willow | 11 | boughs, 31 | |
| Sicilian sumach | 78 | 158 | |
| Malaga sumach | 79 | ||
| Souchong tea | 48 | ||
| Green tea | 41 | ||
| Bombay catechu | 261 | ||
| Bengal catechu | 231 | ||
| Nut-galls | 127 | 46 | |
| Bark of oak, cut in winter | — | 30 | |
| Do. beech | — | 31 | |
| Do. Elder | — | 41 | |
| Do. Plum-tree | — | 58 | |
| Bark of the trunk of Willow | — | 52 | |
| Do. Sycamore | — | 53 | 16 |
| Bark of Birch | — | 54 | |
| Bark of Cherry-tree | — | 59 | 24 |
| Do. Sallow | — | 59 | |
| Do. Poplar | — | 76 | |
| Do. Hazel | — | 79 | |
| Do. Ash | — | 82 | |
| Do. trunk of Span. chestnut | — | 98 | |
| Do. Smooth oak | — | 104 | |
| Do. Oak, cut in spring | — | 108 | |
| Root of Tormentil | — | 46 | |
| Cornus sanguinea of Canada | — | 44 | |
| Bark of Alder | — | 36 | |
| Do. Apricot | — | 32 | |
| Do. Pomegranate | — | 32 | |
| Do. Cornish cherry-tree | — | 19 | |
| Do. Weeping willow | — | 16 | |
| Do. Bohemian olive | — | 14 | |
| Do. Tan shrub with myrtle leaves | — | 13 | |
| Do. Virginian sumach | — | 10 | |
| Do. Green oak | — | 10 | |
| Do. Service-tree | — | 8 | |
| Do. Rose chestnut of Amer. | — | 8 | |
| Do. Rose chestnut | — | 6 | |
| Do. Rose chestnut of Carolina | — | 6 | |
| Do. Sumach of Carolina | — | 5 |
TANNING (Tanner, Fr.; Gärberei, Germ.); is the art of converting skin into [Leather], which see. It has been ascertained, beyond a doubt, that “the saturated infusions of astringent barks contain much less extractive matter, in proportion to their tannin, than the weak infusions; and when skin is quickly tanned (in the former), common experience shows that it produces leather less durable than leather slowly formed.”[66] The older tanners, who prided themselves on producing a substantial article, were so much impressed with the advantages of slowly impregnating skin with astringent matter, that they employed no concentrated infusion (ooze) in their pits, but stratified the skins with abundance of ground bark, and covered them with soft water, knowing that its active principles are very soluble, and that, by being gradually extracted, they would penetrate uniformly the whole of the animal fibres, instead of acting chiefly upon the surface, and making brittle leather, as the strong infusions never fail to do. In fact, 100 pounds of skin, quickly tanned in a strong infusion of bark, produce 137 of leather; while 100 pounds, slowly tanned in a weak infusion, produce only 1171⁄2. The additional 191⁄2 pounds weight in the former case serve merely to swell the tanner’s bill, while they deteriorate his leather, and cause it to contain much less of the textile animal solid. Leather thus highly charged with tannin, is, moreover, so spongy as to allow moisture to pass readily through its pores, to the great discomfort and danger of persons who wear shoes made of it. That the saving of time, and the increase of product, are temptations strong enough to induce many modern tanners to steep their skins in a succession of strong infusions of bark, is sufficiently intelligible; but that any shoemaker should be so ignorant or so foolish as to proclaim that his leather is made by a process so injurious to its quality, is unaccountably stupid.
[66] Sir H. Davy, on the Operation of Astringent Vegetables in Tanning.—Phil. Trans. 1803.
TANTALUM, is the rare metal; also called [Columbium].
TAPESTRY, is an ornamental figured textile fabric of worsted or silk, for lining the walls of apartments; of which the most famous is that of the Gobelins Royal Manufactory, near Paris.
TAPIOCA, is a modification of starch, partially converted into gum, by heating and stirring cassava upon iron plates. See [Cassava] and [Starch].
TAR (Goudron, Fr.; Ther, Germ.); is the viscid, brown-black, resino-oleaginous compound, obtained by distilling wood in close vessels, or in ovens of a peculiar construction. See [Charcoal], [Pitcoal, coking of], and [Pyrolignous Acid]. According to Reichenbach, tar contains the peculiar proximate principles, [paraffine], eupion, [creosote], [picamar], [pittacal], besides pyrogenous resin, or pyretine, pyrogenous oil, or pyroleine, and vinegar. The resin, oil, and vinegar are called empyreumatic, in common language.
Tar imported into the United Kingdom, in 1836, 9,797 lsts. 8 brls.; in 1837, 11,480 lsts. 1 brl. Retained for home consumption, in 1836, 9,639 lsts. 8 brls.; in 1837, 11,686 lsts. 8 brls. Duty received, in 1836, £7,231; in 1837, £8,775.