142 
for, if it is pale and pierced at the top, fubftance, as will be (seh by the following 
the infeéts have left their ceils, which are 
then of no ule as a dye or colour, but it 
may be, better for varnifhes. The fecd- 
lac contains but little of the colouring. 
matter; but fhell-lac contains the leat of, 
all. ms 
I. Effedts of different Menfirua on Lac. 
1. When water is poured on ftick-lac, 
it is tinged with red, and,. with the affift- 
ance of heat, a deep crimfon f lution is 
formed ; but, after feveral fuch operations, 
the flick-lac becomes a mere yeliowifh 
brown fubftance, and the water no longer 
receives any colour. The matter fepa- 
rated from the fick-lac amoun!s to about 
ten per cent. Seed-iac will not afford 
more than two and a half or three per 
cent. and fhell-lac will not yield more 
than one-half per cent. 
2. Alcohol difiolves a confiderable por- 
tion of each of the different kinds of lac 5 
and, when heat is not employed, the dif - 
folved part is refin, combined with iome 
of the colouring-matter ; but if digefied 
with heat, the folution becomes turbid, 
and it is difficult afterwards to obtain it 
in a ftateof tran{parency. The refin may 
be obtained Ly fubjecting the foluticn to 
evaporation or difiiilation, The folution 
formed by digettine flick-lac in alcohol, 
wiithovt heat, 1s of a dark brownifh red 
colour, and-the proportion of refin thus 
diffolved amounts to fxty-feven or fixty- 
eight per cent. The feed-iac yields, when 
very pure, to alcohol, about eighty-eight 
per cent. of refin; and fhx]l-lac, in {mall 
fragments, by fimole digeftion, with alce- 
hol, afforded nearly ninety-one-per cent. 
3. Sulphuric ether does not feem to act 
fo powertully upon jac as-alcohol 5 but in 
certain circumitances it may be advan- 
tageoufly ufed for the purvofe of analyfis. 
4. Concentiated fulphuric acid aéis ia 
the firft inftance on the colouring- matter 
of lac ; the part feparated is infoluble, re- 
dembling coal, and a eonfiderable quantity 
of fulphuric.acid gas is evolved, 
In this way Mr. Hatchet has given the 
refult of experiments on lac with the other 
‘acids, both mineral and vegetable, and 
alfo with the alkalies. 
IT. Analytical Experiments on Lae. 
This fecond fe€tion gives a full account | 
of the analyfes of the feveral ‘kinds of 
Jac; from which are deduced the proper- 
ties of the colouring extraét of lac, of the 
xefin of lac, of the gluten of lac, and of 
the wax of lac, all four of which fab- 
ftances‘are found ia the feveral varicties of 
fac, though the refin is the predominant 
Proceedings of learned Societies: - 
[ March t, 
tables : i 
Stick-lac, 100 parts. 
Beeliti ey. ie) ae vy Fok alt ee 
Colourmg-extradt, 2 . 2. 10 
BA PRM me SD ain Wd Re yd 6 
Glateng oc Wo oe a oe 
Extraneous iubftanées, ..  . «6.50 
96.00 
Seed lac, 100 parts. 
relia. eg! pal We iene eee 
Colouring extracts". 7. = Sane 
Wasieec cee ce ie ut eee 
luten, e e e ° e e 2 
95.50 
Shell.lac, 100 parts. 
FGI ge itu) et Me St te 
Colouring extract, © =. .. 6.50 
Way a as Ola Cen 
Gloteny:,  .. “6 ) «epee nee 
6.20 
As a general refult, -it fhould Be fated, 
that lac confifts principally of réfiin, mix- 
ed with certain proportions of a peculiar 
kind of wax, of gluten, and of colouring- 
extract. Hence it may be denominated 
a cero-refin, mixed with gluten and co- 
Jouring-extrac. i 
III. General Remarks. . ey 
Although lac is indifputably the pro- 
dugtion of infeS&ts, yet it pofleffes few of 
the characters of animal fubfances, The 
greater part of its aggregate properties, 
as well as of its component ingredients, 
are fuch as appertain to vegetabie bodies. 
Lac, or, as it is improperly called, gum- 
lac, is manufaftured by the natives of 
india into rings, beads, and other female 
ornaments. When formed into fealing- 
wax, itis employed as a japan, and for 
different coloured varnifhes, The colour- 
ing part is formed into lakes for painters; 
a fort of Spanith-wcel for the ladies is.alfo 
prepared with it; and, as a dying mate- 
rial, it is in general ufe. ‘The refnous 
part is even employed to form grind- 
_fiones, by melting it, and mixing with it 
three pafis of fand. For making polith- 
ing grindtiones, the fand is fifted through 
fire mruflin. inst 2 eet 
The folution of Jac in water may be 
employed as a varnith, which is equal in 
durability, and other qualities, tothofe 
prepared with alcohol.” It is aifo of great 
ufe as a vehicle for colours 5 of courfe, If 
many arts and manvfaftures, the folutions 
of Jac will be found of much utility 3 for, 
like mucilage, they may be diluted with 
; water 5 
. 
‘ 
