Derivation

Collodion is a solution of 4 parts of pyroxylin in 70 parts of stronger ether, and 26 parts of alcohol. Pyroxylin or gun cotton is prepared by adding a mixture of nitric and sulphuris acids to cotton freed from impurities.

Collodion is a colorless, syrupy, and very inflammable liquid, with a strong ethereal odor. By long standing and exposure, or when applied to a surface, it deposits a thin, transparent and strongly contractile film, which is insoluble in water or alcohol. It should be kept in glass-stoppered bottles. It is applied by means of a camel's-hair brush. When it becomes too thick, it may be diluted by a solution consisting of ether, 3 parts, alcohol, 1 part.

Medical Properties And Action

It is serviceable as an emollient, and its action is mechanical, as it draws together and holds in apposition divided parts, and protects such, as well as abraded or denuded surfaces, from contact with the air. As the ether it contains evaporates, the surface of the part to which it is applied is constringed, and a degree of pressure is thus established, which is very useful in moderating vascular action, promoting absorption, and changing the course of pus which may already be formed into a direction more desirable. On account of the liability of collodion to crack and peel off, these objections have been obviated by the use of what is known as Flexible Collodion - Collodium Flexile - (collodion, 92 parts, Canada turpentine, 5 parts, castor oil, 3 parts), which is softer and more pliable and elastic.

Therapeutic Uses

Collodion is very useful in ulcers, fissures, incised wounds, abraded surfaces, erysipelas, skin diseases, etc.

Dental Uses

Collodion is a very useful application in dental practice, to prevent alveolar abscesses from discharging externally on the face; for such a purpose, it is applied in successive layers, so as to act as a compress, and, by moderating the vascular action, cause absorption, or such a change in the direction of the discharge as will induce it to open in the mouth. It is also employed in combination with carbolic acid, as an application for odontalgia; when introduced on cotton, it acts as a temporary rilling; it has also been employed for arresting the mucous secretion during the operation of filling cavities near to or under the margin of the gum, but the rubber dam has superseded it in this respect. Combined with iron and other agents, it forms a styptic preparation.

In the dental laboratory, collodion, in the form of a colored preparation, is employed to coat the surfaces of the plaster models of plastic work, and when not applied too thick, it protects the plaster surface, and also prevents an unsightly rubber surface on that part of the plate which is adapted to the mucous surface of the mouth. When this preparation becomes too thick for use, it may be diluted with a solution of 3 parts of ether to 1 part of alcohol.

Collodion is precipitated by carbolic acid.

Cantharidal Collodion - Collodlum cum Cantharide - is composed of cantharides (Spanish flies), in powder 60 parts, flexible collodion, 85 parts, commercial chloroform, q. s. The addition of one per cent. of Venice turpentine to cantharidal collodion will prevent the disagreeable, and, at times, painful contraction of the preparation on drying.

Like cantharides, cantharidal collodion, when locally applied, excites inflammation of the skin and mucous membrane, which terminates in a copious secretion of serum under the cuticle. It produces a blister in the same time as an ordinary blistering plaster, and is applied with greater facility, and is better adapted to cover uneven surfaces, and retains its place more certainly. It acts much more readily if the evaporation of the ether is prevented by a piece of oiled silk placed over the surface immediately after the application of the collodion.

Dental Uses

Cantharidal collodion is a valuable application in periodontitis, applied to the gum over the root of the affected tooth, by means of a camel's-hair brush, previously removing all moisture from the surface, and protecting the lips and cheeks, until the ether it contains has evaporated, and an artificial cuticle is formed. The blister which rises on the gum should be punctured with a needle. The counter-irritation thus produced relieves the periosteal inflammation.

Iodized Collodion - Collodium Iodicum - (collodion,

Dental Uses 934

iodine, gr. xx) forms a good solution of iodine for external use.

Dental Formulae

For Odontalgia.

Acidi carbolici cryst,

Collodii......aa

Signa

To be applied on cotton.

Signa 935Signa 936

For a Styptic.

Collodii .... partes 100 Acidi carbolici . partes 10 Acidi tannici . . partes 5 Acidi benzoici . partes 5 M. SlGna. - To be applied to the bleeding surface by means of a camel's-hair brush.

Signa 937

For a Styptic.

Collodii......

Tinct. ferri perchloridi Olei ricini • • • . . gtt. ij. M. Signa. - To be applied to the bleeding surface, or, on cotton, to the alveolar cavity.

For a Styptic.

Acidi tannici, Alcoholis, AEthens . . . . aa, parts aeq. M. Then add as much pyroxylin as the solution will dissolve.

Signa 938Signa 939Signa 940

Crystallin is the name of a collodion, in which methyl alcohol takes the place of ethyl alcohol. Crystallin differs from ordinary collodion in that it does not dry so quickly: it leaves a thin transparent cuticle, and a pure article of methyl alcohol should be employed in preparing it to prevent the unpleasant, penetrating odor of impure alcohol. Philip recommends the following formula for "flexible crystallin."

Castor oil...............4 parts

Canada balsam.............2 parts

Crystallin................40 parts.

Signa 941

Crystallin varnish, impervious to air, can be prepared as follows:

Crystallin................30 parts

Castor oil...............4 parts

Zinc oxide...............8 parts.

Signa 942