: 



7G LEtTtfCB. 



has been called Lactucarium, and differs from the Thridace of the 

 French, which is an extract, obtained from the bruised shoots. 

 Lactucarium, when dry, is hard and brittle like gum, but quickly 

 assumes a pasty consistence, if exposed to the open air. Dissolved 

 in distilled water, the filtered solution is clear and of a brownish 

 colour; it strongly reddens litmus paper; with ammonia, it yields 

 a white, fiocculent precipitate, and a copious precipitate is pro- 

 duced in it by an infusion of gall-nuts.* It affords by analysis, 

 resin, mucilage, wax, caoutchouc, and a narcotic principle analo- 

 gous to morphine. 



Mr. Probart has communicated to Dr. Parist the following 

 method of procuring Lactucarium : — 



u I have the Cos Lettuce planted about eight inches asunder in rows, be- 

 tween which there i3 sufficient space to enable persons to pass up and 

 <lo\vn without injuring the plants. I commence my operations just before 

 the plant is about to flower, by cutting off an inch of the stem ; the milky 

 juice immediately exudes and is collected on pieces of wove cotton, about 

 half a yard square. As soon as this becomes charged, it is thrown from 

 time to time iuto a vessel containing a small quantity of water, which, when 

 sufficiently impregnated, is evaporated at the common temperature of the 

 atmosphere, by exposure in a number of shallow dishes. The lactucarivm 

 in a few hours is found adhering to the vessels in the form of an extract, 

 but differing from every other in all its sensible properties ; this method 

 enables me to collect lactucarium with great facility and despatch, but it 

 is still attended with considerable expense, as the proportion of milky 

 product is necessarily very small, and the price of the medicine conse- 

 quently high. This consideration led me to make further experiments.for 

 the purpose of ascertaining whether an extract might not be obtained from 

 the plant, possessing all the properties of lactucarium, when administered 

 in large doses, and which could be introduced at a comparatively trifling 

 cost. In prosecuting this inquiry, 1 found that the plants contain most 

 of the milky juice when they have flowered and the leaves are beginning 

 to assume a yellow hue, and I observed that when cut down, the milky 

 juice assumes for the most part a concrete form, having subsided in the 

 bark of the stalk and in the old leaves; a circumstance which accounts for 

 the extreme bitterness of these parts. I was naturally led from these cir- 

 cumstances to choose the above period for my operations, and to select 

 those parts only of the plant for my extract, rejecting the substance of the 

 stalk and the young sprouts. My method of procuring the extract is as 

 follows : I first macerate the parts in water for twenty-four hours, and 

 then boil them for two, after which I allow the clear decoction to drain 

 . . 



* Magendie's Formulary, translated by Gregory, p. 173. 

 f Pharmacologia 1833, p. 51."). 



