LAC 
of which the hard body of this refin will be found refolved 
into a purple colour. This may yet again be dried, and 
when dried mult be reduced to powder, which powder will 
afford a fine ftrong tinfture to fpirit of wine, being boiled 
in it in a tall glal's in a fand-heat for two or three hours. 
And by this procefs ftrong tinctures may be made from 
myrrh, amber, gum, juniper. Sec. which will yield no 
tinfture of ftrength to fpirit of wine alone, if treated in 
the ufual way. A fpirituous tinflure of ftick-lac was for¬ 
merly fometimes given as a mild reftringent and corrobo¬ 
rant in female weakneffes, and in rheumatic and fcorbutic 
diforders. But the principal medicinal ufe of this concrete 
was as a topical corroborant and antifeptic, in laxities and 
fcorbutic bleedings, and ulcerations of the gums. Some 
employed for this purpofe a tincture of the lac in alum- 
water ; others a tinfture made of vinous fpirits, impreg¬ 
nated with the pungent antifcorbutics. The college of 
Edinburgh directed an ounce of the powdered lac, with 
half an ounce of powdered myrrh, to be digelted in a 
fand-heat, for fix days, in a pint and a half of fpirit of 
feurvy-grafs. 
The gum-lac has been lately ufedasan ele&ric, inftead 
of glafs, for electrical machines. 
Lac (artificial), Laoue, or Lake, is alfo a name given 
to a coloured fubftance, drawn from feveral flowers ; as 
the yellow from the flower of the juniper, the red from 
the poppy, and the blue from the iris or violet. The 
tinctures of thefe flowers are extracted by digefting them 
feveral times in aqua vitae, or by boiling them over a ftove- 
fire in a lixivium of pot-afhes and alum. The principal 
lakes are, Carmine, Florence-lake, and lake from Madder. 
For the preparation of Carmine, four ounces of finely- 
pulverized cochineal are to be poured into four or fix 
quarts of rain or diftllled water, that has been previoufly 
boiled in a pewter kettle, and boiled with it for the fpace 
of fix minutes longer; (fome advife to add, during the 
boiling, two drams of pulverized cryftals of tartar.) Eight 
fcruples of Roman alum in powder are then to be added, 
and the whole kept upon the fire one minute longer. As 
foon as the grofs powder has fubfided to the bottom, and 
the decodlion is become clear, this latter is to be carefully 
decanted into large cylindrical glafles covered over, and 
kept undifturbed, till a fine powder is oblerved to have 
fettled at the bottom. The fuperincumbent liquor is then 
to be poured off from this powder, and the powder gra¬ 
dually dried. From the decanted liquor, which is ftill 
much coloured, the reft of the colouring-matter may be 
feparated by means of the folution of tin, when it yields 
a carmine little inferior to the other. 
For the preparation of Florentine-lake, the feditnent of 
cochineal that remained in the kettle may be boiled with 
the requifite quantity of water, and the red liquor like- 
wife that remained after the preparation of the carmine 
mixed with it, and the whole precipitated with the folu¬ 
tion of tin. The red precipitate mull be frequently edul¬ 
corated with water. Excluflvely of this, two ounces of 
frelh cochineal, and one of cryftals of tartar, are to be 
boiled with a fufficient quantity of water, poured off clear, 
and precipitated with a folution of tin, and the precipitate 
wafhed. At the fame time two pounds of alum are alfo 
to be diffolved in water, precipitated with a lixivium of 
pot-alb, and the white earth repeatedly walhed with boil¬ 
ing water. Finally, both precipitates are to be mixed to¬ 
gether in their liquid ftpte, put upon a filter, and dried. 
For the preparation of a cheaper fort, inftead of cochineal, 
one pound of Brafil-wood may be employed in the preced¬ 
ing manner. 
Madder-lake , which was mentioned long ago by Neri, 
and has been fince difeovered afrelh by Margraff, is made 
by diffolving two ounces of Roman alum in fix pounds of 
boiling water, and to this adding two ounces of fine madder, 
with which the water is fuffered to boil once or twice more, 
and then to Hand for fome time in digeftion. The decoction 
being afterwards filtered, a folution of alkali is to be mix¬ 
ed with it till no farther precipitation enfuss. See farther 
under the article Pigment. 
LAC <27 
LA'C A, a town of Africa, in the country of theFoulies: 
ten miles north-weft of Goumel. 
LACA'BEN, a town of Afiatic Turkey, in the province 
of Aladulia: thirty miles fouth-fouth-well of Malaria. 
LACANI'TIS, in ancient geography, a country of 
Afia, in Cilicia, according to Ptolemy, who places in it 
one city, viz. Irenopolis. 
L AC AR ACOON'DA, a town of Bengal: ten miles 
fouth of Nagore. Lat. 23. 48. N. Ion. 87. 27. E. 
LACA'RIA, a fmall town of Italy, in the eafiern part 
of Lucania, fouth of Heraclea, and near the gulf of Ta- 
rentum ; founded by a colony of Phocseans, and celebrated 
for its good wine. 
LA'CAS, a town of the ifland of Cuba: fifteen miles 
weft of Villa del Principe. 
LAC'CA HER'BA. See Imfatiens. 
LACCABI'VE FSLANDS) a group of fmall iflands in 
the Indian Sea ; the neareft about 120 miles from the coaft 
of Malabar. Thefe iflands are fuppofed to be what Ptole¬ 
my called lnjulee Numero XIX. The Nineteen Iflands; 
but in fail they are thirty-two ; all of them fmall, and 
covered with trees; they are rocky on their fides, moftly as 
if laid on a bottom of fand, attended with reefs, and the 
channels between them very deep ; they are commonly 
vifited by Englilh (hips, in their way from India to the 
Perfian Gulf, or Red Sea. The principal traffic of thefe 
iflands is in the produce of the cocoa-palm, fuch as the 
oil, cables, and cordage; and in fifti, which is dried and. 
fent to the continent of India, from whence they get 
rice, See. in return. They alfo trade to Mafcat in large 
boats; and bring back, in return for their commodities, 
dates and coffee. Ambergris is often found floating off 
thele iflands. Lat. 10. o. to 12. 40. N. Ion. 71. 15. to- 
73. 30. E. 
LAC'CIC, adj. Partaking of the natureof lac; prepared 
from lac. 
Laccic Acid, a fubftance that was firll introduced to 
the notice of chemifts by Dr. Pearfon. It is obtained, 
from a peculiar compound called white-lac, which Dr. An- 
derfon of Madras difeovered to be the product of fome 
infefls of the Coccus tribe. Small quantities of it W'ere 
fent to Europe about the year 1789; and, at the requeft 
of fir Jofeph Banks, an examination of it was undertaken, 
by Dr. Pearfon, and the refult of his inquiries appeared 
in the Philofophical TranfaCtions for 1794. The lac, in 
its natural (late, is of a grey colour; and occurs in pieces 
of from three to fifteen grains, in weight. Many of its 
properties prefent confiderable refemblance to thofe of 
bees’ wax; and Dr. Pearfon is of opinion, that thefe fub- 
llancesare very nearly allied to each other, differing only- 
in the proportion of their conftituents. A curious cir- 
cumitance, connected with this point, is, that, the infedft 
which fecretes the lac alfo produces honey; but the phe¬ 
nomena attending the appearance of the latter produdfc 
have not been examined with the attention which they 
merit. To procure the laccic acid, it is merely neceflary 
to expofe the lac, as afforded by the coccus , to a heat juft 
fufficient to liquefy it. A reddifh watery fluid will fepa- 
rate, having the fmell of newly-baked hot bread; and it 
is this fubftance which conftitutes the acid under inquiry. 
The following are fome of its properties. At the tempe¬ 
rature of 6o°, it has a fpecific gravity of 1-025.. Paper 
ftained with litmus and turnfol is reddened by it. It pofi 
felles a faline tafle, and is fomewhat bitter; but is not in 
the fmalleft degree four. By expofure to the air it be¬ 
comes muddy, and depofits a fmall quantity of fediment. 
Dr. Pearfon diltilled 250 grains ofi it, and afterwards eva¬ 
porated the product until it grew turbid. Or. Handing 
lome hours, acicular cryftals were produced, having a bit- 
terifh tafle, which amounted to about ^i^-th of the 
weight of the fluid employed. The acid dillolves carbo- 
nat of foda with effervefcence; and by evaporation yields 
cryftals which are deliquefeent. It produces a purplifh 
tint on being mixed with lime-water, but no fediment ap¬ 
pears. Tinflure of galls caufes a green precipitate; and 
with acetat of lead a rgddifa powder is depofited. This 
forms- 
