Collodion. A solution of Pyroxylin (Gun Cotton) (C36H22,8 NO4,O30) in Ether, mixed with one-third of its volume of Rectified Spirit. Introduced by Mr. May-nard, of Boston, in 184S, as a substitute for adhesive plaster. A colourless highly inflammable liquid, with ethereal odour, which dries rapidly upon exposure to the air, and leaves a thin transparent film, insoluble in water and rectified spirit.

* Surg. Dict., 7th Ed., art. Gonorrhoea.

Quoted by Pereira, vol ii. part i. p. 163.

Dict. Pract. Med, vol. ii p. 310.

§ Ibid. vol ii. p. 823.

II See Medico-Chir. Rev.. July 1836, p. 161.

¶ Med. Quarterly Review, vol. ii. p. 183.

Prep. The Brit. Pharm. directs that fl. oz. v. of Sulphuric Acid be mixed with fl. oz. v. of Nitric Acid in a porcelain mortar. One ounce of Cotton is then immersed in the mixture, which is to be stirred lor three minutes with a glass rod until the cotton is thoroughly wetted by the Acids. The cotton is then transferred to a vessel containing water, and washed with fresh supplies of water, until the washing ceases to give a precipitate with Chloride of Barium. The product (Pyroxylin) is then to be drained on filtering-paper and dried in a water bath. To prepare Collodion, oz. j. of Pyroxylin is to be dissolved in a mixture of fl. oz. xxxvj of Ether with fl. oz. xij. of Rectified Spirit. Another mode of preparing Collodion is as followa: - Take Cotton3v., Sulphuric Acid fxvj., Nitre x. The Acid and the Nitre should be mixed in a china capsule, and the cotton being added, the mixture should be agitated for the space of three minutes with a glass rod. It should then be well dried. Gun cotton, thus prepared, should be used in making Collodion in the following manner: - Take Gun Cotton 3ij., 8ulphuric Ether fiv., Rectified Spirit f3ij., mix well together, and keep in a closely-stoppered bottle. (Miahle.*)