T A N 
T A N 
hip and put down every third or fourth day, 
[for a fortnight or three weeks, in order to de- 
stroy the epulennis-of the skin. The hair is 
then scraped oft', and the excrescences being 
removed, they are put into a pit of water 
| impregnated with pigeon-dung, called a 
Igrainer, forming an alkal ne ley, which in a 
| week or ten days soaking out the lime, grease, 
[ and saponaceous matter (during which pe- 
[ riod they are several times scraped over with 
[ a crooked knife, to work out the dirt and 
filth), softens the skins, and prepares them 
for the reception of the ooze. They are then 
| put into a pit of weak ooze, in the same man- 
ner as the hides, and' being frequently han- 
; died, are by degrees removed into a stronger, 
and still stronger liquor, for a month or six 
l weeks ; when they are put into a very strong 
i ooze, with f.esh bark ground very fine, and 
I at the end of two or three months, according 
| to their substances, are sufficiently tanned; 
when they are taken out, hung on poles, 
- dried, and are fit for sale. These skins are 
■ afterwards dressed and blacked by the cur- 
riers, and are used for the upper leathers of 
siioes, boots, &c. 
The lighter sort of hides, called dressing 
hides, as well as horse-hides, are managed 
, nearly in the same manner as skins; and are 
i; used for coach-work, harness-work, &c. &c. 
Much light has been thrown by modern 
ij chemists upon the theory of tanning, though 
it does not appear that any considerable im- 
| provements have been made in the practice 
of this art. M. Seguin, in France, has par- 
■ ticularly distinguished himself by his re- 
;[ searches on this subject. 
In 1795, Mr. William Desmond obtained 
j a patent for practising Seguin’s method in 
England. He obtained the tanning principle 
by digesting oak-bark or other proper 111 a- 
terial in cold water, in an apparatus nearly 
similar to that used in the saltpetre- works. 
That is, the water which has remained upon 
I the powdered bark for some time, in one ves- 
j sel, is drawn off by a cock, and poured upon 
fresh tan; This is again to be drawn off, and 
poured upon other fresh tan ; and in this way 
I the process is to be continued to the fifth ves- 
j sel. The liquor is then highly coloured, and 
marks from six to eight degrees upon the 
hydrometer for suits. This he calls the tan- 
ning lixivium. 
The criterion for ascertaining its strength, 
is the quantity of the solution of gelatine 
which a given quantity of it will precipitate. 
Isinglass is used for this purpose, being en- 
tirely composed of gelatine. And here it 
may be observed, that this is the mode of as- 
certaining the quantity of tanning principle 
in any vegetable subdance, and consequently 
how far each may be used as a substitute for 
oak-bark. * ' 
The hides, after being prepared in the 
usual way, are immersed for some hours in a 
Weak tanning lixivium of only one or two de- 
grees ; to obtain which, the latter portions of 
the infusions are set apart, or else some of 
that whichhas been partly exhausted by use in 
tanning. The hides are then to be put into 
a stronger lixivium, where, in a few days, 
they will be brought to the same degree of 
saturation with the liquor in which they are 
immersed The strength of the h’quorLwil! 
by this means be considerably diminished, 
and must iherefore be renewed. When the 
hides are by this means completely saturat- 
ed, that is, perfectly t. lined, they are to be 
removed, and slowly dried in the shade. 
It has been proposed to use the residuum 
of liie fanning lixivium, or the exhausted 
ooze (which contains a portion of gallic acid, 
this forming a constituent part of astringent 
vegetables), for the purpose of taking off the 
hair; but this liquor seems to contain no 
substances capabie of acting upon the epi- 
dermis, or of loosening the hair; and when 
skin is depilated by being exposed to it, the 
effect must really be owing to incipient pu- 
trefaction. 
The length of time necessary to tan leather 
completely, according to the old process, is 
certainly a very great inconvenience; and 
there is no doubt that it may be much 
shortened by following the new method. It 
has been found, however, that the leather so 
tanned has not been so durable as that which 
has been formed b_\ a slower process. 
TANTALITE. This mineral has been 
found in Finland, in the parish of Kimilo. 
It lias been long known ; but before the 
analysis of Ekeberg, was mistaken for an ore 
of tin. Found in irregular crystals, which 
seem to be octahedrons. Colour between 
bluish grey and blackish grey. Surface 
smooth, with some lustre. Lustre metallic. 
Fracture compact. Streak blackish grey, ap- 
proaching brown. V ery hard. Not magnetic. 
Specilic gravity 7.953. Composed of the 
oxides of tantalium, iron, and manganese. 
TANTALIUM. Mr. Ekeberg, a Swed- 
ish chemist qtj considerable eminence, has 
lately discovered a new metal constituting a 
component part of two minerals, found in the 
parish of Kiinifo in Finland. The first of 
these minerals, which he calls tantalite, lias a 
bluish or blackish grey colour, crystallized 
confusedly, with a metallic lustre and com- 
pact fracture. It is very hard, and its spe- 
cific gravity is 7.953. It has been long known, 
and mistaken for an ore of tin. 
The other mineral, called yttro-tantalite, is 
found in small kidney-form masses. It is of 
a deep-grey colour, has a metallic lustre, and 
a granular fracture. It is not hard. Its spe- 
cilic gravity is 5.130. 
From each of these minerals Mr. Ekeberg 
extracted, by a chemical analysis, a white 
powder, which he ascertained to be the oxide 
of a peculiar metal, to which he gave the name 
of tantalium. 
When this white oxide of tantalium is 
strongly heated along with charcoal in a cru- 
cible, it yields a button moderately hard, 
which has the metallic lustre externally, but 
within is black and destitute of brilliancy. 
The acids convert it again into the state of 
white-coloured oxide. 
This oxide does not alter its colour, though 
heated to redness. Its specific gravity is 6.500. 
It is not acted on by acids, nor is it soluble in 
any of them. It was this insolubility in acids 
which induced Ekeberg to give it the name 
of tantalium, from the fabled punishment of 
Tantalus. 
This oxide combines with the alkalies ex- 
cept ammonia, and forms with them com- 
pounds soluble in water. When melted with 
phosphat of soda and borax, it forms with 
them glasses destitute of colour. Such a* - e 
the only properties of this metal hitherto 
published. 
T A P 771 
The resemblance between the oxides of 
tantalium and coiumbium is striking. '1 lie 
only property in which they differ is, the in- 
solubility of the first in acids; but we know 
not what acids Ekeberg tried, and Mr. Hat- 
chett found the oxide oi coiumbium insoluble 
in nitric acid. 
TANTALUS, or tars, a genus of birds of 
the order graliax The generic character is, 
bill long, subulate, roundish subarched ; face 
naked; nostrils oval; feet four-toed, palmate 
at the base, There are 23 specie^ titemost 
remarkable are : 
1. The loculator, or wood ibis: (1.) face 
bluish ; bill reddish ; legs, quill and tail fea- 
thers, black; body white. (2.) Head and 
neck white, varied with yellow ; body black; 
belly cinereous. (3.) Wing-coverts white, 
with a black blotch in the middle. Inhabits 
New Holland, and the warmer parts of Ame- 
rica. It is three feet long; is very slow in 
flight, and stupid ; sits on trees, and feeds 
on herbs, seeds, fruits, fish, and reptiles. 
The flesh is very much esteemed. 
2. 1 he leucephalus, or white-headed ibis, 
inhabits India ; and every year before the 
. rainy season sets in, it sheds its rosy feathers. 
3. The ibis, or Egyptian ibis, inhabits in 
vast numbers the lower part of Egypt, and is 
held sacred by the inhabitants for its use ia 
clearing the land of reptiles and insects, which 
are left after the inundation of the Nile. It 
rests in an erect posture, and is said to de- 
stroy the young of the crocodile. 
4. The melanocephalus, or black-headed 
ibis, is a very beautiful bird that inhabits" 
India. See Plate Nat. Hist. fig. 391 . 
Tantalus’s cup. See Hydraulics. 
TAPE-v/orm. SeeTasNiA. 
TAPESTRY, a kind of woven bangings 
of wool and silk, frequently raised and en- 
riched with gold and silver, representing 
figures of men, animals, landscapes, his- 
tories, &c. 
The invention of tapestry seems to haye 
come to us from the Levant ; and this ap- 
pears the more probable, as the workmen 
concerned in it were called, at least in France, 
sarrasins, or sorrasinois. It is supposed that 
the English and Flemish, who were the first 
that excelled in making tapestry, might 
bring the art with them from some of* the 
crusades, or expeditions against the Saracens, 
Tapestry-work is distinguished by the work- 
men into two kinds, viz. that of high, and that 
of low warp ; though the difference is rather 
in the manner of working than in the work 
itself, which is in effect the same in both, 
only the looms, and consequently the warps, 
are differently situated ; those of the low 
warp being placed flat and parallel to the ho- 
rizon, and those, on the contrary, of the hLh 
warp, erected perpendicularly. * The English 
antiently excelled all the world in the tapestry 
of the high warp. 
The manufacture of tapestry of the high 
tvarp. The loom, whereon it is wrought, is 
placed perpendicularly. It consists of four 
principal pieces ; two long planks or cheeks 
of wood, and two thick rollers or bean s. The 
planks are set upright, and the beams across 
them, one at the top, and the other at the 
bottom, or about a foot distance from the 
ground. They have each their trunnions 
by which they are suspended on the planks* 
' and are turned with bars. Jn each roller is a 
5 E 2 
