40 
LACTUCA VIROSA. 
Properties. The garden lettuce, when young, and at the time 
it is usually cut for salad, possesses an abundance of a bland, cooling, 
pellucid fluid ; but as the flower stem shoots up, this fluid becomes an 
opaque, milky juice, of an exceedingly bitter taste, which, by evapo- 
rating in the air, and becoming dry, turns brown. According to the 
analysis of Mr. John, of Berlin, this juice has been found " to 
** consist of water, caoutcliouc as its principle solid constituent, a 
*' trace of resin, a small quantity of bitter extractive, and phosphates, 
*' muriates and sulphates." 
From this analysis we are led to infer that it is a very inert sub- 
stance, as caoutchouc, which he gives as its principal solid constituent, 
has little or no medicinal properties ; we know however that this 
plant possesses very active properties, which are found to reside in 
an alkali, analogous to morphia, and which seems to have been 
overlooked by Mr. John. Indeed the soporific powers of lettuce 
were known to the ancients ; but we are indebted to Dr. Coxe, of 
Philadelphia, for having first submitted it to the test of experiment, 
since when, through the perseverance and recommendation of Dr. 
Duncan, senior, the preparations of lettuce have found a place in 
Iwo'o^ the British Pharmacopoeias. 
Mr, Young, surgeon of Edinburgh, who has taken great pains to 
bring the various preparations of lettuce to perfection, gives the 
following, as his process. 
Having made an incision in the flowering stem, he collects the 
juice, as it exudes, on a sponge, from which it is again expressed, 
and speedily dried by exposure to the atmosphere ; to this he gives 
the name of lettuce opium : it occurs in commerce in round hard 
masses of a deep-brown colour, with a strong virose smell, and 
bearing a great resemblance to Turkey opium, but none to an 
extract: in this way it is now prepared on a very large scale. 
It is evident, that by this process of Mr. Young, the virtues of 
the plant, as an opiate, are obtained in the most natural state ; but 
the great expense of the preparation, has given rise to various 
attempts to lessen it. 
Dr. Probart, we are told, collects the milky juice, as it exudes 
from the cut stem, upon pieces of wove cotton, about half a yard 
square, and from time to time, throws them as they become charged, 
into a vessel containing a small quantity of water, which when 
sufticiently impregnated is evaporated by simple exposure in shallow 
vessels. By this process a very pure extract, free from the caou- 
tchouc, is furnished ; but it is still expensive. Dr. Probart further 
observed, that after the plants have flowered, and the leaves are 
beginning to assume a yellow hue, the milky juice assumes a concrete 
