"This is a modification of this process proposed by William M. Thomson (1883). The percolator is an elongated cone, which may be taken apart in sections, each section forming a percolator, ending below with a perforated diaphragm of the same diameter as that of the top portion of the next section; the powder to be exhausted is packed in the different sections, and the liquid percolating through from above, as it leaves one section, is again uniformly distributed over the powder contained in the next.

"A process for the preparation of fluid extracts without the use of heat deserves a passing notice, since from the employment of a very powerful press it is perhaps better adapted for the manufacturer than for the pharmacist. It was devised by N. S. Thomas (1865), and consists in moistening the ground drug with a portion of the menstruum, and after sufficient maceration expressing the liquid. The operation of maceration and expressing is repeated several times until the proper quantity of fluid extract is obtained.

Fig. 390.   Glass Percolators with Supply and Receiving Bottles

Fig. 390. - Glass Percolators with Supply and Receiving Bottles.

Fig. 391.   Real's Solution or Filter Press

Fig. 391. - Real's Solution or Filter Press.