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stance in all the properties above detailed, 
it can scarcely be doubted that it is nothing 
else than a peculiar- modification of coagu- 
lated albumen. 
2. The cutis is a thick dense membrane, 
composed of fibres interwoven like the tex- 
ture of a hat. When it is macerated for 
some -hours in water, and agitation and pres- 
sure are employed to accelerate the effect, 
the blood, and all the extraneous matter 
with which it was loaded, are separated from 
it, but its texture remains unaltered. On 
evaporating the water employed, a small 
quantity of. gelatine may be obtained. No 
subsequent maceration in cold water has any 
farther effect. When distilled it yields the 
Same products as fabrina. The concentrated 
alkalies dissolve it, converting it into oil 
and ammonia. Weak acids soften it, render 
it transparent,. and at last dissolve it. Nitric 
acid converts it into oxalic, acid and fat, 
while, at the same time, azotic gas and prus- 
sic acid are- emitted. When heated it con- 
tracts,, and then. swells, exhales a fetid odour, 
.anddoaves a dense charcoal, difficult to in- 
cinerate. By spontaneous decomposition in 
■ water or moist earth, it is converted into a 
fatty 'matter, and into ammonia, which com- 
pose a kind of soap. When allowed to re- 
main long in water, it softens and putrefies, 
being converted into a kind of jelly. W hen 
long boiled in water it becomes, gelatinous, 
and dissolves completely, constituting a vis- 
cid liquor, which, by. proper evaporation is 
converted into glue. Hence the cutis of 
animals is commonly employed in the ma- 
nufacture of glue. 
From these facts the cutis appears to be a 
peculiar modification of gelatine enabled 
to resist the action of water, partly by the 
compactness of its texture, and partly by the 
viscidity of the gelatine of which it is form- 
ed ; for those skins which dissolve most rea- 
dily in boiling water afford the worst glue. 
"Mr. Hatchett has observed, that the visci- 
dity of the gelatine obtained from skins is 
nearly inversely as their flexibility, the sup- 
plest hides always yielding the weakest glue ; 
but this glue is very soon obtained from 
them by hot water. The skin of the gel is 
very flexible, and affords very readily a 
great proportion of gelatine. The skin of 
the shark also readily yields abundance of 
gelatine & and' the same remark applies to 
the skins of thfc hare, rabbit, calf, and ox ; 
the difficulty of obtaining the glue and its 
goodness always increasing with the tough- 
ness of the hide. The hide of the rhinocer- 
os, which is exceedingly strong and tough, 
far surpasses the rest in the difficulty of so- 
lution and in the goodness of its glue. When 
skins are boiled they gradually swell and as- 
sume the appearance of horn, then they dis- 
splve slowly. 
It is from the skin or cutis of animals that 
leather rs formed ; and the goodness of the 
leather, or at least its strength, depends in 
some measure on the toughness of the hides. 
Those easily soluble, as seal-skins, afford a 
weaker leather than those which are more 
difficultly soluble in water. The process 
by which the skins of animals are converted 
into leather is called tanning. It seems to 
have been known and practised in the ear- 
liest ages; but its nature was totally unknown 
till after the , discovery of the tanning prin- 
ciple by Seguin. That chemist ascertained 
that leather is a compound of tan and skin ; 
that it is to the tan that leather owes its in- 
solubility and its power of resisting putrefac- 
tion. The subject has lately engaged the 
attention of Mr. Davy, who has examined 
it with his usual ingenuity, and- added seve- 
ral important facts to our former knowledge. 
When skins are to be tanned, the first step 
of the process is to deprive them of their 
hair and cuticle. This is either done by 
steeping them in water till they begin to 
putrefy, or by steeping them in lime and 
water. The lime seems to combine with the 
cuticle, and to render it brittle and easily 
detachable from the "hide. It produces the 
same effect upon the hair and the matte* at 
its root. When the hides have been steep- 
ed for a sufficient time, they are taken out, 
the hair, cuticle, &c. scraped off, and then 
they are washed in water. 
After this preliminary process, the skins 
are subjected to different treatment accord- 
ing to the kind of leather which is to be 
made. 
The large and thick hides are introduced 
for a short time into a strong infusion of 
bark. They are then said to be coloured. 
After this they are put into water slightly 
impregnated with sulphuric acid, or with 
the acid evolved during the fermentation of 
barley and rye. This renders them harder 
and denser than they were before, and fits 
them for forming sole-leather. Mr. Davy 
thinks, that by this process a triple com- 
pound is formed of the skin, tan, and the 
acid. The light skins of cows, those of 
calves, and all small skins, are steeped for 
some days in a lixivium made by the infusion 
of pigeon’s dung in water. This lixivium is 
called the grainer. By this process they are 
rendered thinner, and softer and more proper 
for making flexible leather. Mr. Davy con- 
siders the effect of this lixivium to depend 
upon the fermentation which it undergoes ; 
for dung that has undergone fermentation 
does not answer the purpose. After these 
preliminary processes, the skins are exposed 
to the action of the infusion of bark till they 
are converted into leather. The infusion 
of oak-bark contains two ingredients, name- 
ly tan and an extractive. The first is more 
soluble than the second. Hence in saturated 
infusions there is a much smaller proportion 
of tan than of extractive ; whereas in weak in- 
fusions, the extractive bears a greater pro- 
portion to the tan. Mr. Davy considers it 
as doubtful whether the infusion of oak-bark 
contains any gallic acid. This chemist has 
ascertained, that the hides extract both the 
tan and extractive from the infusion, and 
leave nothing behind but pure water, pro- 
vided they are employed in sufficient quan- 
tity. Hence it is obvious, that both the tan 
and extractive must enter into the compo- 
sition of leather. The extractive gives the 
hide a brown colour, but does not render it 
insoluble in boiling water ; the tan renders 
it insoluble, but its colour continues whitish. 
Hence it is likely that the lightest kinds of 
leather contain little else than tan, while 
the brown kinds contain both tan and ex- 
tractive. While the hides are allowed to 
remain in the infusion of bark, they combine 
of course with tan and extractive, and the 
new compound is leather. Hence the rea- 
son ©f the increase of its weight. 
Calf-skins, and those hides which are pre- 
pared by the grainer, are first steeped in 
weak infusions of oak-bark, and gradually 
removed to stronger and stronger, till they 
are completely impregnated, which takes 
up from two to four months. As the weak 
infusions contain a greater proportion of 
extractive, the consequence of this process 
is, that the skin combines in the iirst place 
with a portion of it, and afterwards with the 
tan. When saturated solutions of tan are 
employed, the leather is formed in a much 
shorter time. This was the process recom- 
mended by Seguin ; but it has been observ- 
ed, that leather tanned in this way is more 
rigid and more liable to crack than leather 
tanned in the usual way. Hence it is like- 
ly, as Mr. Davy has observed," that the ujiion 
of the extractive is requisite to form pliable 
and tough leather. Leather rapidly tanned 
must be less. equable in its texture than lea- 
ther slowly tanned, as the surface must be 
saturated with tan before the liquid has time 
to penetrate deep. Mr. Davy has ascer- 
tained that skins, while tanning, seldom ab- 
sorb more than one-third of their weight of 
vegetable matter. 
Skms intended for sole leather are gene- 
rally kept from the first in an infusion pre- 
served nearly saturated by means of the 
strata of bark, with which they alternate. 
The full impregnation requires from ten to 
eighteen months. It is likely from this pro- 
cess that sole leather contains a greater 
proportion of tan than soft leather. While 
drying, it is smoothed with a rolling-pin, 
and beaten with a- mallet, which must add 
considerably to its density. 
3. As to the rete mucosum, or the mu- 
cous substance situated between the cutis 
vera and epidermis, its composition cannot 
be determined with precision, because its 
quantity is too small to admit of examination. 
It is known that the black colour of negroes 
depends upon a black pigment, situated in 
this substance. Oxyinuriatic acid deprives 
it of its black colour, and renders it yellow. 
A negro, by keeping his foot for some time 
in water impregnated with .that acid, depriv- 
ed it of its colour, end rendered it nearly 
white ; but in a few days the black colour 
returned again with its former intensity. 
This experiment was first made by Dr. Bed- 
does on the fingers of a negro. See Ana- 
tomy, Physiology, and Tanning. 
CUTTER of the tallies, an officer of the 
exchequer, whose , business is to provide 
wood for the tallies, to cut or notch the sum 
paid upon them ; and then to cast them 
into court to be written upon. 
CUTTING, in heraldry, is used for the 
dividing a shield into two equal parts, from 
right to left, parallel to the horizon, or in 
the fesse-wav. 
Cutting in zvood, a particular kind of 
sculpture, or engraving, denominated from 
the matter on which it is employed. That 
sort of engraving which is called cutting in 
wood, was the first invented. It is used for 
initial letters, head and tail pieces of books, 
and even for schemes and other figures, to 
save the expence of engraving on copper : 
and for prints and stamps for paper, calicoes, 
linen, &c. The art of cutting in wood was cer- 
tainly carried to very great perfection about 
one hundred and fifty years ago, and lias 
siuce been revived with very great success 
