Volume 2

The Edinburgh new dispensatory containing 1. The elements of pharmaceutical chemistry. 2. The materia medica ... 3. The pharmaceutical preparations and compositions. Including translations of the London pharmacopoeia of 1825 ... Edinburgh pharmacopoeia ... 1817; Dublin pharmacopoeia ... 1807 / By Andrew Duncan.

  • Duncan, Andrew, Jun., 1773-1832
Date:
1826
Catalogue details

Licence: Public Domain Mark

Credit: The Edinburgh new dispensatory containing 1. The elements of pharmaceutical chemistry. 2. The materia medica ... 3. The pharmaceutical preparations and compositions. Including translations of the London pharmacopoeia of 1825 ... Edinburgh pharmacopoeia ... 1817; Dublin pharmacopoeia ... 1807 / By Andrew Duncan. Source: Wellcome Collection.

    35/966 (page 33)
    ‘ Solids are separated from solids in various ways. a. Finer from coarser powder of the same kind. Sift= ing, tamisation. . 6. Round from ill-shaped grains ; as in lead shot. c. Lighter from heavier powders of different kinds : 1. Winnowing. | 2. Separation of metallic from earthy particles. 3. Elutriation. d. lron-filings from other metallic powders by means of a magnet. — 101. Sifting.—Powders of different degrees of fineness are separated, . a. For the sake of the finer powder in most instances ; b. For the sake of the coarser powder, as in the making of Species. | - 102. It is performed by a sieve; the finer powder being made to pass through its interstices, while the coarser pow- der is retained. 103. The materials of which sieves are composed are very various. a. Metals; iron, copper, brass, silver. b. Wood, chip, split cane, hempen cloth, linen or cotton. c. Split whalebone, hair-cloth, silk, (¢amis ). 104, Sieves are of various degrees of fineness, according to the purpose for which they are used. a. Coarse; called screens, riddles. b. Fine; sieves, searces, bolters. 105. A sieve consists essentially of the sifting material, at- tached to a frame, which determines its form. The frame is sometimes square, but most commonly a cylindrical hoop, over one end of which the sifting material is stretched. In bolting mills it is wrapped around an open cylindrical frame. 106. Compound sieves have a close lid and receiver, so that nothing, either valuable or deleterious, can escape. 107. Dusting bags are formed of the sifting material, and are generally inclosed in a very close box, which serves as a receiver for the fine powder which is shaken through the bag. 2 108. The manipulation by which the fine powder is made to pass through the sieve is various : The sieve itselfis either shaken gently, or struck upon a hard body *; orif the sieve be cylindrical, it is either whirled round upon its axis, or it isileft at rest, and the fine powder forced through by means of brushes carried round upon an axis. * This is objected to by Cayentou, as forcing through a coarser powder. C