2560 
or nearly fo, when full, and gives it a dip 
oa the fide of the burner, forming an 
angle of about forty-five degrees when 
empty; the axis is alo adjulted, with 
refpeét to the depth of the lamp, that it 
may feed itfeif evenly, by the gradual de- 
{cending of the burners. 
Obfervaticn. Weare not aware of any 
grear advantages that will accrue to the 
public from this patent invention. 
MR. WILLIAM ALISON'S (LONG-LANE, 
BERMONDSEY) for MANUFACTUR- 
ING. SPANISH OF MOROCCO LEa- 
THER. 
This article is manufactured from the 
South-American horfe-hides, which be- 
ing dricd in the climateof that country, all 
the natural moifture is parched up. To 
reduce them to a proper degree of foftnefs, 
they are put into {oft ftinking water for 
five or fix days, when they are to be taken 
up and {pread over the tanner’s beam, and 
worked over the flefly fide with a knife. 
‘They are then to be put back again into 
the {ame flinking water for three or four 
days more, or till they are fufficienily (oft; 
after which they are to be put into lime- 
water for fourteen days, taking care, by 
moving them, that every part of the hide 
receive equal benefir.. The hair will now 
come off, and the thick part of the hides 
mut be fhaved, fo as to render them of 
equal fubftance. hey are then to under- 
go the fame procefs as that adopted in 
making goat’s fkins into this leather, by 
putting them into warm water mixed with 
dogs’ dung. While in this they mutt be 
moved conftantly, and worked over a 
beam, with akoite, on both fides, to clan 
them from greafe and filth, which will 
take about two hours. Yo make them 
mellow and of a fair colour, they may be 
put into werm water, with a layer of bran 
between each hide; in this they muff re- 
main till they begin to ferment. They 
muft then be taken up and worked. clean, 
by brufhing them with a knife over both 
flefh .and grain tides, when they are fit to 
be tanned and finifhed. 
Proceedings of Learned Societies, 
[Oa 1, 
MR. HITCHCOCK’S (HOLBORN) for cote 
verling SKINS of PARCHMENT ang 
VELLUM iato LEATHER, and making 
the LEATHER WATER-PROOF. 
The kins of vellum or parchnient are- 
to be foaked twenty-four hours in water, 
they are then to be rinced, and fteeped an 
equal time ina liquor confitting of twent 
gallons of water, one pound and a half of 
white copperas, bruifed fine, ane ounce of 
fal-ammoniac, and a pound of cream of 
tartar, which is fuficient for fifty fkins, 
The liquor is then to be ftrained off into 
another veflel, and with it, are to be mix. 
ed a pint of fpirit of marine fal, one 
pound of fpirit of nitre, and ten pounds 
of oil of vitriol. The ikins put into this 
folution are to be contiantly ftirred about 
tll they have difcharged all the lime ; they 
are then to be immeried for twelve hours 
in clearr iver water, and aiterwards rinced 
out as dry as poffible. 
_ Now put them into a deco&tion made of 
twenty pounds of oak bark, five pounds of 
elm bark, three pounds of lignum vite 
chips, three pounds of faflafras, and feven 
pounds of fumach, put into a large cop. 
per with twenty gailons of water; boil the 
whole gently for twenty-four hours, ftrain 
it and let it cool until blood warm: then 
dip the fkins in it one after another tor 
about five minutes, after which put them 
in tan-pits, with a weak folution of oak 
bark, or with fumach, where they are 
to remain till properly tanned, or about 
four or five days. 
To make them ‘water-proof, they mutt 
be {caked about the fame number of days. 
in nut or Jinfeed oil, then wrung out as dry 
as poflible, and brufhed over feveral times 
with a compoiition mace in the following 
manner: to red-lead, litharge, copperas, 
fugar of lead, refin, bees wax and pitch, 
each one pound, add feven gallons of nut, 
linfeed cr Ath oil, and boi them in an iron 
or earthen pot till the whole is as thick as 
treacle; when cold it is to be fpread on 
the leather, or brufhed on when warm, or 
fpread when cold three or four times ; and 
in afew days it will be fit for ufe, j 
“PROCEEDINGS OF LEARNED SOCIETIES. 
ROYAL SOCIETY. 
R. YOUNG laid before this learned 
bedy in the courfe of la winter a 
valuable paper containing experiments 
and calculations relative to phyfi:ai op- 
tics. The propofition which he istinded 
‘to eftablith was, ** that fringes of colour 
are produced by the imterference of twa 
portions of light ;’’ in defence of which 
his experiments are fo fimple as to be re- 
peated with great cafe whenever the fun 
ihines, and without the intervention of 
any 
