538. In Pruritus Scroti, Mr

E. Wilson states that pencilling the parts with the Compound Tincture {ante) will be found useful.

.539. Benzoic Acid. Acidum Benzoicum. HO,C14H5O3. Flowers of Benjamin. An Acid obtained from Benzoin by sublimation.

Med. Prop. and Action. Stimulant, particularly of mucous surfaces; the vapour causes great irritation of the air-passages. In the system it is converted into Hippuric Acid by the assumption of the elements of Glycocoll (C14H6O4 + C4H5,NO4 = C18H9NO6 + 2HO). (Garrod.) It renders theurine acid and stimulating. It is best administered internally in the form of Ben-zoate of Ammonia. (See Ammonia} Benzoas.)

Offlc. Prep. Tinctura Camphorse cum Opio (see Opium).

Dose of Benzoic Acid, gr. x. - gr. xx.

540. Therapeutic Uses

Calculous diseases. Mr. Ure observed that when Benzoic Acid was taken into the system, it was converted into Hippuric Acid, and that in this form it was excreted in the urine. He considered that this change was effected by the Benzoic Acid acting upon Uric Acid, and therefore he proposed it as a means of correcting the Uric or Lithic Acid diathesis. Dr. Keller showed this supposition to be incorrect; and the experiments of Dr. Booth § on this subject give the following results: - 1, that the introduction of Benzoic Acid into the system does not in any way affect the Uric Acid; 2, that the time required for the conversion of Benzoic into Hippuric Acid, and its subsequent appearance in the urine, is about twenty minutes, and the effect lasts from four to eight hours; 3, that the amount of Hippuric Acid exceeds that of the Benzoic by about one-third; 4, that urea is not in combination with Hippuric Acid in the urine. These results prove the inutility of Benzoic Acid as a remedy for Uric Acid diseases. Dr (iarrod,|| in repeating these experiments, found that he could produce a very acid state of the urine, enabling that fluid to hold in solution a large amount of phosphatic salts. He employed it in a case of paraplegia, when the urine was highly alkaline, and deposited a large amount of the phosphates. He administered gr. xl. of the acid four times a day, and the phosphatic deposits soon became lessened, and in a few days entirely ceased. The urine also, when voided, was acid.

* Loc. cit.

Diseases of the Skin, p. 344.

Mod. Chir. Trans. vol. xxiv. p. 30.

§ Trans. of American Philosoph. Society, vol. ix. || Lancet, Dec. SO, 1843.

"When the medicine was discontinued, the abnormal state of the urine did not return. Mr. Ure * has lately published a case of Inertia of the Bladder, with stagnation of urine (that fluid being strongly ammoniacal, and containing a large quantity of ropy mucus and some pus), in which the administration of gr. x. of the acid, in a mucilaginous draught, three times a day, was attended with the best effects.

541. In Gout, Benzoic Acid Was Advised By Mr

Ure and Dr. Prout, to prevent the deposition of, and to remove when formed, the masses of urate of soda, which so commonly occur about the joints of gouty subjects. It was recommended on the supposition that Benzoic Acid converted the Uric Acid deposits into Hippuric Acid; but if the conclusions of Drs. Keller, Booth, and Garrod be correct, this medicine will exercise no remedial effect in these cases. (See the preceding section.)

542. In Incontinence Of Urine In Children, Dr

Delcour speaks highly of the value of Benzoic Acid. He relates two cases successfully treated when all other remedies had failed. As a remedy in Jaundice, Benzoic Acid has recently attracted much attention It is applicable only to jaundice arising from suppression of the biliary secretion. Dr. Harley mentions some cases in which benefit followed its use.