Fluid Extracts. This form of medicinal extracts was introduced into the United States Pharmacopoeia in 1850, for the first time as a distinct class of preparations. Their distinctive character is the concentration of the active ingredients of a substance into a small bulk and in liquid form. Their advantages consist in greater convenience of administration, and in the fact that, not having been subjected to excessive evaporation, the active principles they contain are less liable to have suffered injury by heat. The main difficulty lies in their liquid form increasing the liability to undergo spontaneous decomposition; this is counteracted in some cases by the addition of sugar, in others by alcohol, and in others again by a mixture of both. Some fluid extracts have a tendency to deposit matter when combined with sugar, rendering the extract turbid or cloudy in appearance ; instead of sugar, Mr. Alfred B. Taylor has proposed the use of glycerine, •which, while it has the same preservative influence, possesses the property of dissolving the matter which would be deposited by the use of sugar. Fluid extracts are obtained by percolation, and the menstruum used is alcohol or alcohol and water, the proportions of each depending on the nature of the substance to be extracted. The price of alcohol has greatly increased since 1860, and a regard to economy has probably, in some cases, induced deviations in officinal preparations. This point will probably receive due consideration at the next revision of the Pharmacopoeia.

4572. Grahame's Method of Percolation

4572.     Grahame's Method of Percolation. Professor Grahame, of the Maryland College of Pharmacy, has proposed a modification of the displacement process which may be thus stated: Reduce the substance, by contusion, to a powder which will pass through a sieve of 40 meshes to the linear inch (if of close texture a sieve of 60 meshes is to be preferred); now add just sufficient of the menstruum to dampen the powder without wholly destroying its mobility; this usually requires about one-fourth as much menstruum as of the powder. Transfer to a glass funnel with a plug of cotton in the neck, and pack it with little or much pressure, according to its tenacity or disposition to adhere (more firmly when alcohol or ether is the menstruum than when water is to be used); if the particles of the moistened powder move freely on each other, the packing should be with as much force as a glass vessel will bear, the whole of the powder being introduced at once, and packed with a pestle or packing-stick. The whole quantity of the menstruum may now be poured on, or to the capacity of the funnel, and the process allowed to proceed to completion, without in any case repassing the first portions of the liquid. By this process, if carefully followed, very concentrated solutions are obtained. Indeed, most of the fluid extracts may be completed with little or no evaporation.