Note 505 — PHARMACOLOGIA. (continued 4)

“I have the Cos Lettuce planted about eight inches asunder in rows, between which there is sufficient space to enable persons to pass up and down 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 into 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 Lactucarium, 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 dispatch, but it is still attended with considerable expense, as the proportion of milky product is necessarily very small, and the price of the medicine consequently high, and therefore not within the reach of general practice. This consideration led me to make farther 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 enquiry, I 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 circumstances 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 through a sieve, without using any pressure; this is then evaporated, as far as it can be done with safety, and the process is finished in shallow dishes, in the manner above described, for obtaining Lactucarium. This extract, which I have called “Extractum Lactucæ Concentratum,” is of course less powerful than Lactucarium, but it possesses all the properties in larger doses, and it has been found equally useful in a number and variety of cases, and is not more than a sixth part of the price.”

Mr. Probart has retired from trade, but I have just learnt that the same article is now prepared, by a similar process, by Mr. Selway, Chemist, of New Cavendish Street, and the specimens which I have received authorise me to recommend it for trial. A concentrated tincture is also prepared.

The “Succus Spissatus Lactucæ sativæ,” of the shops, must of necessity be almost inert, since it is commonly prepared at that period when the plant contains none, or very little of the milky juice; and even if the Lettuce be employed at a more mature season, it must still fail to afford an extract of any strength, as it is merely the expressed juice, and that too of the whole plant indiscriminately, and will be found to contain a very minute proportion of Lactucarium, the great bulk being nothing more than inspissated green juice.