72 LAC 
ladleous circle, yet are there more by four than Philo men¬ 
tions. Brown. —Lacteal; conveying chyle.—The lungs are 
fuitable for refpiration, and the lablccus veffels for the re¬ 
ception of the chyle. Bentley. 
LAC'TES, f. The fmall guts ; the fweetbre'ad ; the 
row; the milt of fifties. Not much ufed. Phillips. 
LACTES'CENCE, f. Tendency to milk, or milky co¬ 
lour.—This ladlefcence does commonly enfue, when, wine 
being impregnated with gums, or other vegetable concre¬ 
tions, that abound with lulphureous corpufeles, fair water 
is fuddenly poured upon the folution. Boyle on Colours. 
LACTES'CENT, adj. Producing milk, ora white juice. 
-—Amongft the pot-herbs are fome laElcfcent plants, as let¬ 
tuce and endive, which contain a wholefome juice. At. 
buthnot. 
LAC'TIC, adj. Partaking of the nature of milk: pre¬ 
pared from milk. 
Lactic Acid. See the article Chemistry, vol. iv. 
p. 360. 
LACTIF'EROUS, adj. \lac zndfero, Lat.] What con¬ 
veys or brings milk.—He makes the breads to be nothing 
but glandules, made up of an infinite number of little 
knots, each whereof hat 1, its excretory veflel, or lablijerous 
duft. Ray on the Creatio an -An appellation given to plants 
abounding with a inilf ’'juice, as the fow-thiftle and the 
like. But the namer jSjflaBiferous, or laElefcent , is given to 
all thofe plants whicn abound with a thick coloured juice, 
without regarding whether it is white tar not ; for in 
fome it is yellow, in others red.—Moft lactiferous plants 
are poifonous, except thofe with compound flowers, which 
are generally of an innocent quality. Ency. Brit. 
LACTIF'IC, or Lactifical, adj. Producing milk. 
Scott. 
LACTOM'ETER, f. The pame of an inftrument for 
the purpofe of afcertaining the different qualities of milk. 
It was invented by Mr. Dicas, mathematical inftrument 
maker, in Liverpool; and a defcription of it is given in 
the Survey of the County of Lancafter. This lactometer 
is contrived fo as to afcertain the ricnnefs of milk from 
its fpecific gravity compared with water, by its degree of 
warmth taken by a ftandard thermometer, on comparing 
its fpecific quality with its warmth, on a fcale conftrufted 
for this particular purpofe; and by which, if the principle 
be right, may be difcovered, not only the qualities of the 
milk of different cows, paftures, food, as turnips, potatoes, 
grains, &c. but alfo, probably, which may be the bell milk 
or bell paftures for butter, and which for cheefe. This 
inftrument, however, is but in its infancy; and, till repeat¬ 
ed experiments have confirmed its efficacy, it would be 
premature to give a detailed account of it. At prefent it 
is made ufe of in the Liverpool workhoufe in afcertaining 
goodnefs of the milk confumed there. 
LACTU'CA, J. [a ladle, from its milkinefs.] Let¬ 
tuce; in botany, a genus of the clafs fyngenefia, order 
polygamia aequalis, natural order of cornpofitas femiflof- 
culofae, (cichoracese, JuJf.) The generic characters are— 
Calyx: common imbricated, cylindric; fcales very many, 
iharp, membranaceous on the margin. Corolla : com¬ 
pound imbricated, uniform ; corollets hermaphrodite, very 
many, equal. Proper one-petalled, ligulate, truncated, 
four or five toothed. Stamina : filaments five, capillary, 
very fhort; anther cylindric, tubular. Piftillum : germ 
iubovate ; ftyle filiform, length of the ftamens ; ftigmas 
two, reflex. Pericarpium : none ; calyx converging, 
ovate-cylindric. Seeds : folitary, ovate, acuminate, even, 
compreffed. Down capillary ; on a long ftipe, attenuated 
below. Receptaculum : naked.— EJfential Charabler. Ca¬ 
lyx imbricate, cylindrical, with a membranaceous mar¬ 
gin ; receptacle naked ; feeds even, with a Ample ftipi- 
tate down. 
Species. 1. Laftuca quercina, or oak-leaved lettuce: 
leaves runcinate, toothletted, acute, even underneath ; 
ftem fmootli. Root perennial, flelhy. Stem upright, nar¬ 
row, ufually from one to two feet in height, but jibme- 
L A C 
times fix feet high ; even, unbranched, terminated by an 
upright narrow raceme of flowers. Lower leaves run- 
cinated ; upper pinnatifid, with toothletted acute feg- 
ments; they are not at all prickly underneath, and refem- 
ble thofe of Sonchus oleraceus, or common fow-thiftle. 
Flowers as in L. lativa^yellow ; calyx fmooth, fometimes 
dotted with red ; corollets five-toothed; down white. 
Ray, who cultivated it in his garden at Cambridge, re¬ 
marks, that the leaves refemble thofe of the oak, are of a 
deeper green than thofe of the garden-lettuce, fmalier, and 
few at the root, before it grows up into a ftalk. In its 
whole habit it approaches nearer to the wild than the gar¬ 
den lettuce. Native of Sweden and Germany. 
2. Laftuca intybacea, or endive-leaved lettuce : leaves 
runcinate, tooth-ciliafe, blunt, embracing; ftem panicled. 
The whole plant is fmooth and milky. From an annual 
root the ftem rifes two or three feet in height, round, up¬ 
right, green, leafy at bottom, dividing at top into rod-like 
leaflefs branches. Native of South America. 
3. Laftuca fativa, or garden-lettuce: leaves rounded; 
ftem-leaves cordate; ftem corymbed. Leaves large, milky, 
frequently wrinkled, ufually pale green, but varying much 
in colour, form, &c. in the different varieties. Stem ftrong, 
round, two feet or three quarters of a yard in height, 
bearing abundance of fmall yellow flowers. The feeds 
are a little fmalier than in L. lcariola, but more turgid, 
narrowing very much below, marked with feven crenu- 
late ftreaks, afh-bay coloured or whitifh. The down is 
very foft and fugacious, and placed on a ftipe the length 
of the feed. The native place of the garden-lettuce is 
unknown ; and it is not improbable that it may be a mere 
creature of cultivation, from one of the wild ones. The 
firft printed authority we have for its cultivation in Eng¬ 
land is that of Turner in 1562; but we probably had it 
much earlier. 
The common or cultivated lettuce has long been cele¬ 
brated for its cooling and wholefome properties ; and, as 
it contains a milky juice of an opiate nature, it in conle- 
quence promotes fleep. Lettuce is alio in fome degree 
laxative and aperient, and is proper in hot bilious dilpo- 
fitions. The feeds of lettuce are of an emollient nature, 
and are ranked atnoygft the cold feeds of the old materia 
medica. They unite with water by trituration into an 
emullion or milky liquor, which has nothing of the ape¬ 
rient bitternefs of the milky juice of the leaves, and is 
nearly fimilar to the emullion of almonds : this emullion 
of lettuce has however been fuppofed of a mere refrige¬ 
rating nature than that of almonds, and hence has been 
preferred in heat of urine and other diforders ariling frotn 
acrimony or irritation. The feveral varieties cultivated 
in kitchen-gardens for ufe are, 1. Common or garden let¬ 
tuce. 2. Cabbage-lettuce. 3. Cilicia. 4. Dutch brown. 
5. Aleppo. 6. Imperial. 7. Green capuchin. 8. Ver- 
Tailles, or upright white Cos. 9. Black Cos. 10. Red 
capuchin. 11. Roman. 12. Prince. 13. Royal. 14. 
Egyptian Cos. Garden-lettuce is named in German gar¬ 
ten/a/at ; in Dutch, tuinfalade, or latuw ■, in French, laitue 
cultivee, ou commune. Labluca a little changed is the pre¬ 
vailing* word in the European languages for lettuce : in 
Ruffian, Danilh, and Swedifti, it is laktuk ; in Italian, lat - 
tug a ; in Spanilh, lechnga ; in Portuguefe, leituga. 
It has long been known that lettuce poffefles narcotic- 
properties ; till lately, however, none had extrafted from 
it a fubftance poffeffing all the properties of opium. Dr. 
Coxe of Philadelphia has proved (American Philofophi- 
cal Tranlaftions, vol. iv.) that the infpiffated milky juice 
of the common lettuce is real opium, and, according to 
every appearance, of a better quality than the eaftern ; 
for the principal virtues of this medicine are believed to 
refide in the extra&ive matter ; and, by comparative expe¬ 
riments, it was found that ten grains of extractive mat¬ 
ter were taken up by two ounces of rain-water from twenty 
grains of lettuce-opium ; while, from the fame quantity 
of common opium, only nine grains were taken up by an 
1 equa$ 
