58 
warmth before immerfion of the fkins. 
“Thefe are then to be tanned in the com- 
mon way with oak bark, or oak and fu- 
mach, wafhed and dried. ‘To make the 
leather water-proof it muft be firft foaked 
for five or fix days in linfeed or nut oil, 
and after this has been wrung out, the 
{kin is to be repeatedly fineared with a 
‘compofition, made by melting together 
feven pounds of nut or linfeed oil, with 
one pound of each of the following ingre- 
dients, namely, red lead, litharge, fugar 
of lead, white vitriol, bees-wax, rofin, 
and pitch. ; : 
Obfervations.—The objeé in the above 
procefs is, firft to reduce the fkin to its 
rriginal ftate, by foftening its texture, 
diffolving cut the lime, &c. next to give 
it a body by means of a ftrong, tanning, 
and laftly,. to make it water-proof, by 
means of various ingredients that refift 
moifture. Some of the receipts are fuffi- 
ciently complex, but in all, the ingre- 
dients appear powerful, and are probably 
efficacious. 
—=xiiz==— 
MR. HOTCHKISS, for @ NEW MECHANI- 
CAL POWER for LIFTING WEIGHTS, 
Ge. 
The method in which this power is ap- 
plied is to make a capftan, or fimilar ma- 
chine, with two barrels of unequal dia- 
meter, to’ faften a rope round the large 
barrel, pafs it through a pully to which the 
weight is attached, and wind it round the 
fmaller barrel in a contrary diregtion. 
Hence, as the weight bears upon each bar- 
rel in the proportion of their diameters, 
and as it is taken of from the power ap- 
plied in, the proportion which the fmaller 
bears to the larger barrel, it is only the 
difference between the two that conftitutes 
the real reftftance to be overcome. There- 
fore, the nearer in fize the diameters are, 
the more power will be faved, but they 
muft not be made quite equal, otherwife 
the weight to be raifed would not at all 
advance. The moft convenient applica- 
tion of this power is to cranes, prefles, 
and other machines where velocity of 
movement is not required. It is not ne- 
ceflary to have both the barrels on one 
axis, but they may be placed parallel to 
ach other, and working againft each 
other by toothed wheels, ‘or cogs, whereby 
the revolution of one will be mede in the 
contrary dire¢tion to that of the other. 
MR. TURNBULL, for an IMPROVEMENT 
inthe COMMON PROCESSESO/ BLEACH- 
” QNG COTTON OF LINEN PIECES. ¢ 
The Patentee begins his procefs by 
a 
New Patents lately £ nrolléd. 
[Febos, 
taking any kind of earth which is eafily 
mixable with water, fuch as clay, marle, 
or fuller’s earth, or if that cannot be had, 
any kind of foft mud and the like, which 
is put into a boiler to evaporate the moif- 
ture, dried, again mixed with water, and 
paficd through fieves to enfure a requifite’ 
finenefs. This is then mixed with quick- 
limé, which is flacked in the earthy pulp, 
and fornis the materials for the feveral 
backings which the cloth is to undergo. 
‘The pieces are to be worked in the back- 
ing tubs for anumber of times, alternating 
this with rinfing and fring, as in the 
long eftablifhed method of bleaching, and 
expofing to the air onthe bleaching ground. 
The only difference in the procefs here 
employed is the admixture of earthy mud 
or clay to the lime, whereby the corrofive 
force of the latter is moderated, and may 
therefore be ufed more freely. In the Jaft 
buckings pot-afh is alfo added to the 
earthy mixture. This procefs, therefore, 
unites that of fulling with foaping, or 
wafhing with alkaline lye, and it appears 
very probable, that fuch a union may be 
a faving of time, and-of expence of alkali, 
which. is:the heavieft article. 
a 
MR. THIVILLE, for az INVENTION Of a - 
LAMP or LIGHT. 
The invention f{pecified in this account 
at confiderable length, confilts, in its mo# 
material point, of an extenfion of the con-_ 
trivance of lenfes fometimes placed before 
carriage and ftreet lamps, in order to con- 
tinue the general advantage of increafing 
the apparent body of the flame and the 
real quantity of light emitted by it, with 
that of directing the cone of rays produced 
by the refringent power of the glafs, upon 
any object in any direction where it may 
be required. ‘Fhe Patentee, inftead of 
making the refracting glafes of a convex 
or fpherical form, gives them:a cylindrical 
or oblong fhape, fometimes truncated, or 
elfe a conical form, where the object is to 
divert to a particular fpot all the rays 
which pafs through the glafs. The form 
and direction of thefe glaffes muft be en- 
tirely regulated -by the known laws of ca- 
toptrics, as for inftance, when the light 
is to be thrown above the horizontal plane 
of the burner, the refraGting glafs mutt be 
inade conical, with the apex downwards; 
and vice verfa, if a lower part is to be 
iilaminated. Sometimes the convex furs 
face of the refracting glafs may. becut into 
facets, in order to encreafe the apparent 
number of the flames as well as the real 
quantity of light. . It is obvious, that bp 
thus confulting the laws of the reflection 
and 
> 
