TANNING. 
hides; they are from ten to eighteen months 
in tanning, and are used for the soles of 
shoes. 
Skins is the general term for the skins of 
calves, seals, hogs, dogs, &c. These, after 
being washed in water, are pot into lime- 
pits, as before mentioned, where they are 
taken np and put down every third or 
fourth day, for a fortnight or three weeks, 
in order to dilate the pores and dissolve the 
gelatinous parts of the skin. "Ihe hair is 
then scraped off, and the flesh and excres- 
cences being removed, they are put into a 
pit of water impregnated with pigeon-dung 
(called a grainer or mastring,) forming a 
«trong alkaline ley, which in a week or ten 
day, soaking out the lime, grease, and sapo- 
naceous matter (during which period 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 manner as the hides, and being fie- 
quently handled, are by degrees removed 
into a stronger and still stronger liquor, for 
a month or six weeks, when they are put 
into a very strong ooze, with fresh bark 
ground very fine, and at the end of two or 
three months, according to their substance, 
are sutficiently tanned ; when they are 
taken out, hung on poles, dried, and fit for 
sale. These skins are afterwards dressed 
and blacked by the enrriet ; and are used 
for the upper-leathers of shoes, boots, &c. 
The lighter sort of hides, called dressing 
hides, as well as liorse-hides, are managed 
nearly in the same manner as skins; and 
are used for coach- work, harness-work, &c. 
Having given some account of the pro- 
cess as is commonly used in this country, 
we proceed to one recommended by M. Se- 
giiin in France, who is supposed to have 
done much towards simplifying and render- 
ing perfect the art. In order to give cur- 
rency to the knowledge which he had ob- 
tained by a long course of experiments and 
actual practice in the business, he exhibited 
without reserve all that he had discovered, 
and at the same time actually executed his 
processes on the large scale, furnishing gra- 
tuitously skins and tan, in order that others 
who were witnesses to his plans might re- 
peat for themselves, and at their leisure, 
the experiments they had seen him go 
through. We shall give an outline of his 
plan and reasoning on this important sub- 
ject. 
Skins swell up, and become soft, by 
moisture, which renders them permeable to 
water. Hence they are easily .destroyed by 
the putrid process which ensues, and they 
become dry and brittle when the moisture 
is evaporated. Accident, no doubt, occa- 
sioned the discovery of the means of pre- 
venting these inconveniences by the use of 
certain vegetable substances, particularly 
the bark of oak. It was seen that skins / 
prepared with these substances acquired 
new properties; that without losing their 
flexibility they became less permeable to 
water; more firm, more compact, and in 
some measure incapable of putrefaction. 
These observations gave birth to the art of 
the tanner. This art, no doubt of high an- 
tiquity, because founded on one of the ear- 
liest wants ,of man in society, comprehends 
a succession of processes which was execut- 
ed by habit and imitation, without a know- 
ledge of the essential objects. The pre- 
paration of skins accordingly required seve- 
ral years, and frequently, in spite of the 
care, expense, and slowuess of the opera- 
tion, the tanning, was incomplete; the skin 
formed a soft and porous leather, which 
was soon destroyed by moisture. These 
defects essentially sprung from ignorance of 
the true principles of this operation, be- 
cause no discovery had been made respect- 
ing the action of tan upon tlie skin, and the 
circumstances, or conditions, which might 
accelerate or retard the process. 
To arrive at this knowledge in an accu- 
rate manner, it is necessary to consider, 
first, the nature and properties of tan, and 
secondly, the structure and composition of 
the skin. We stall not enter into the de- 
tail of such precautions as are requisite iu 
the choice of oak bark, the time and man- 
ner of separating it from the tree, preserv- 
ing it, or pulverising it. It will be suffi- 
cient for our object to remark, that water: 
poured into a vessel upon tan acquires, af- 
ter some hours infusion, at the common 
temperature of the atmosphere, a brown 
colour, an astringent taste, and becomes 
charged with the most soluble substances 
contained in the tan ; that by drawing off 
the water, and adding a similar quantity to 
the tan repeatedly, the whole of the soliu- 
ble parts may be successively extracted, 
the water ceases to acquire colour, and 
there remains in the tub a mere fibrous 
matter, or parenchymatous texture, insolu- 
ble iu water, and no longer adapted to pro- 
mote the operation of tauniug, This resi- 
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