Collodion, Sensitised. Add to 1 oz. of the plain collodion 6 drams of spirits of wine; 13⁄4 oz. of ether; and 3 drams of iodide and bromide solution (see below). Shake the bottle well; the mixture is then ready, but is improved by being kept four or five hours before using. In hot weather a little more alcohol and less ether; in very cold weather more ether and less alcohol must be used. As sensitised collodion does not keep well, it is better not to mix the plain collodion and the iodide and bromide solution until shortly before required for use.
Iodide and Bromide Solution. Iodide of cadmium 154 grains; bromide of cadmium 54 grains; spirits of wine, 31⁄2 ounces. Pound the iodide and bromide very fine in a mortar, adding the spirit gradually; when the iodide and bromide are dissolved, pass the solution through a filter paper into a bottle. Must be kept in a closely-stoppered bottle.
Collodion, Styptic. Syn. Styptic colloid. (Dr Richardson.) To a saturated solution of tannic acid in alcohol and ether, in equal parts, add as much pyroxylin as the liquid will dissolve.
Collodion, Ves′icating. Syn. Blis′tering collodion, Canthar′idin c.; Collo′dium ves′icans, L. Prep. 1. (Tichborne.) Coarsely powdered cantharides, 6 oz., are placed loosely in a displacement apparatus (provided with a tap to regulate the flow), and treated with ether from methylated spirit, 13 fl. oz., and glacial acetic acid, 2 fl. oz., previously mixed together. After the fluid has passed through, it will be found that the débris has retained by absorption 7 fl. oz., which must be displaced by the gradual addition of methylated spirits of wine, 7 fl. oz. If properly managed, there is not the least danger of the admixture of the spirits with the percolated menstruum, as the animal substance of the flies swells considerably under the prolonged influence of the spirits of wine, so that the same bulk will be insufficient to quite displace the ether. The ethereal solution should be made to measure exactly 15 fl. oz. with a little spirit, and may then be converted into a collodion by the addition of pyroxylin, 1⁄2 oz.
Obs. The glacial acid plays a double part in this preparation. It dissolves the cantharidin, and at the same time gives to the collodion film the essential property of porosity. Ordinary collodion is useless as an excipient, for it produces a tough and contractile film, which really screens the skin from the action of the greater part of the blistering material.
2. (Ilisch.) Cantharidin, 15 gr.; pyroxylin, 20 gr.; rectified ether, 11⁄2 oz.; acetic ether, 1⁄2 oz.; dissolve.
3. (Œttinger.) Ether of cantharides and collodion, equal parts.
Use. Vesicating collodion is used as an irritant. No. 1 was introduced in 1862, and has many advantages over the other two. Mr Tichborne thus described the most effectual method of using it in the ‘Pharm. Journ,’:—“The part upon which the blister is to be raised should be painted with the vesicant
to the desired extent, bearing in mind that the blister produced always extends to about one tenth of an inch beyond the margin of the space covered. Care should be taken to give a coating of considerable thickness, and to ensure this result the brush should be passed over and over again, until about 1⁄2 dr. has been used to the square inch, or less when operating upon a tender epidermis. It is desirable to place over the intended blister a piece of oil silk, or, what is still better, a piece of sheet gutta percha, somewhat larger than the surface painted, as this will stop the exhalations of the skin, and so render it moist and permeable. In ten minutes, or a quarter of an hour if the cuticle is hard, the collodion should be wiped off with a little cotton-wool moistened with ether, when the blister will almost instantly rise.”
COL′LOID. See Dialysis.