CARBOLIC ACID. Since the article on this substance first appeared in the Encycle padia, much has been ascertained regarding its uses, both as a therapeutic agent and as a disinfectant. It has been introduced into the new British pharmacopoeia (1867), where its characters and tests are thus described: "In colorless acicular crystals, which at a temperature of 95° become an oily liquid, having a strong odor and taste resembling that of creosote, which it also resembles in many of its characters and properties. Its specific gravity is 1.065; boiling point, 370°. The crystals readily absorb moisture on exposure to the air, and they are thus liquefied; the acid, however, is but slightly soluble in water, but it is freely soluble in alcohol, ether, and glycerine. It does not redden like litmus paper; a slip of deal dipped into it, and afterwards into hydrochloric acid, and then allowed to dry in the air, acquires a greenish-blue color. It coagulates albu men. It does not affect the plane of polarization of a ray of polarized light." It may be taken internally in doses of from one to three grains in the same class of cases as those in which creosote is prescribed. Its principal uses are as external applications, in which, in various degrees of dilution, it is serviceable ill unhealthy ulcerations, gangren ous sores, ozcena and all fetid discharges, gleet, the destruction of lice, and especially, as prof. Lister has shown, as an application in compound fractures (in which it coagulates all albuminous effusions, and forms a solid crust, impermeable to air, over the broken surface), and to abscesses immediately after they have been opened. Indeed, it is most probable that his investigations on the treatment of abscess will, like those on the treat ment of compound fractures, lead to a total alteration in this department of surgery. The observations of Pasteur and others have shown that, in even apparently the purest air, numerous organic germs are always floating. In a hospital ward, these germs are multiplied to an extraordinary degree. In any wound exposed to the atmosphere (as a compound fracture), decomposition takes place by the action of these germs, and hence it is necessary to introduce the C. A., which has the power of destroying these germs, into the interior. In an unopened abscess, no septic organisms are present, and the object of the surgeon is to guard against their introduction from without, and at the same time to afford a free exit for the discharge of the contents of the abscess. The following are the outlines of prof. Lister's mode of proceeding: A square piece of rag is dipped in a solution of one part of crystallized C. A. and four parts of boiling linseed oil, and is laid upon the skin where the incision is to be made. The lower edge being raised, a scalpel dipped in the oil is plunged into the cavity of the abscess, and a sufficient opening made; and the moment the knife is drawn, the raised part of the rag is dropped upon the skin as an antiseptic curtain, beneath which the pus escapes. The
-cavity of the abscess is firmly pressed, so as to remove as nearly as possible all the exist ing pus, and if it should seem expedient, a piece of lint dipped in the oily mixture may be introduced, so as to check bleeding and prevent primary adhesion of the cut surfaces. "Thus," says prof. Lister, "the evacuation of the original contents is accomplished with perfect security against the introduction of living germs. This, however, would be of no avail unless an antiseptic dressing could be applied that would effectually prevent the decomposition of the stream of pus constantly flowing out beneath it." Ile finds that the most suitable dressing is made as follows: Six tea-spoonfuls of the oily solution are mixed with common whiting (carbonate of lime) so as to form a putty, which is spread upon six inches square of common tinfoil, strengthened with adhesive plaster to prevent its tearing. The tin thus spread withputty is laid upon the skin, so that the middle of it corresponds with the point of incision, the antiseptic rag used in open ing the abscess being removed the moment previously. The tin is then fixed with adhesive plaster, the lowest edge being left free for the escape of the discharge into a folded towel placed over it, and secured with a bandage. The dressing must be removed every day, and a piece of rag dipped in the oily solution must be placed on the incision when the first tin is removed, so as to guard against the possibility of the entrance of germs during the cleansing of the skin with a dry cloth, and pressing out any discharge that may exist in the cavity. If a piece of lint was inserted into the wound, it must be removed when the tin is applied. From the absence of the irritation excited by decomposition, pus almost At once ceases to be formed under this treatment; and large abscesses, after their original contents have been evacuated, often yield in 24 hours only a few drops of serum in the course of a few days. The pharmacopeia gives the glyceride of C. A. (consisting of one part of the acid to four of glycerine) as a good form for local application; but the proportion of acid must vary with the case.
The value of C. A. as a disinfectant was placed beyond all doubt by the investiga tions made at the request of the royal commissioners, who were appointed to obtain information and report on the cattle disease. In the same way, C. A. is highly ser viceable in military camps, on board ship, iu disinfecting dunghills, in purifying the air of sick-rooms, stables, bird-cages, and any place where the germs of disease do or may lurk. It is extensively used for preserving wood, as in railway sleepers. It has recently acquired importance as a source of dye-stuffs, Victoria orange, phenicienne or phenyl brown, coralline, etc. C. A. acts as a powerful poison on animal and vege table life in general. The creosote (q.v.) obtained from coal-tar is often simply a form of carbolic acid.