The elements of medical chemistry : embracing only those branches of chemical science which are calculated to illustrate or explain the different objects of medicine, and to furnish a chemical grammar to the author's Pharmacologia . Filtration. An operation, by means of which a fluidis mechanically separated from consistent particles merelymixed with it. It does not differ from Straining, exceptperhaps in degree. 122. A filtre is a species of very fine sieve, which is per-meable to the particles of fluids, but through which those of thefinest solids are incapable of passing ; hence its use in
The elements of medical chemistry : embracing only those branches of chemical science which are calculated to illustrate or explain the different objects of medicine, and to furnish a chemical grammar to the author's Pharmacologia . Filtration. An operation, by means of which a fluidis mechanically separated from consistent particles merelymixed with it. It does not differ from Straining, exceptperhaps in degree. 122. A filtre is a species of very fine sieve, which is per-meable to the particles of fluids, but through which those of thefinest solids are incapable of passing ; hence its use in separa-ting impalpable powders from suspension in fluids. 123. The instruments for this purpose are constructed ofvarious materials, and in their selection care must be takenthat they be not acted upon by the substances for which theyare employed. For many purposes in pharmacy, as for the straining ofsaccharine and mucilaginous liquors, flannel, or fine woollencloth, or linen, is chiefly used ; the filtre is usually formedin a conical shape, as possessing the advantage of uniting allthe liquor, which drains through into a point, where it maybe readily collected in a receiving vessel (A), thus— 80 1ARISS MEDICAL Flannel filtres are particularly eligiblealso where our object is to preserve thesolid residue, but when the filtred liquoris the valuable product, linen is general-ly preferable, as it absorbs less of the fluid,which is thus obtained ai-o ma more lim-pid state. 124. For smaller processes, and where it is essential tohave the nitres perfectly clean, unsized paper is square piece of this paper, of a size proportionate to thequantity of the substance to be filtred is taken and first dou-bled from corner to corner into a triangle, which by seconddoubling forms again a smaller triangle, and this when open-ed constitutes a paper cone, as here exhibited (Fig. 1) whichis to be supported in a glass funnel (Fig. 2) before the liquoris poured into it. I
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