BORACIC ACID. — Boracic, or boric, acid appears in the form of white, trans lucent or lustrous scales or needles, and is usually prepared by adding hydro chloric acid to a hot solution of borax (sodium borate); when comparatively fresh it exhales a faint odor of henzoin. It has a warm, acrid taste; acid reac tion; and is freely soluble in alkaline media, in oils, and in chloroform; 1 to 3 in alcohol; 1 to 15 in boiling and about 1 to 25-50 in cold water. The solubility in cold water varies so greatly with different specimens as to seem un accountable, but doubtless depends upon the source of the acid, the mode of its manufacture, and the resultant purity or impurity. In 1SS9 Catanis proposed to render the acid more soluble by mix ing 120 parts with 10 of calcined mag nesia and 750 of water, whereby a con siderable proportion of the former is in solution in excess.
From the fact that boracic acid forms borates with most of the alkaloids, it has been advised that they be employed when the acidity of the drug is to be feared.
Preparations and Dose.—Boracic acid, 5 to 15 or 30 grains.
Borate of ammonium, 10 to 20 grains. Borate of sodium (borax), 15 to 30 grains.
Borate of zinc, for external use only.
Physiological Action. — Boracic acid and all its salts are deemed more or less antiseptic, and the former has attained special repute because of its inexpensive ness, general harmlessness, and unirri toting character. But purity is always a matter to be carefully considered, both as regards external and internal use. It is not so commonly employed as an internal medicament, perhaps, as the sodium salt, because of its somewhat pungent and acid taste, and partly be cause it is deemed less convenient to prescribe in aqueous mixtures. In ex
cessively large doses, however, both it and the salts depress the spinal centres. and may produce progressive loss of voluntary and reflex activity without affecting nerve or muscle. Schiff is re sponsible for the statement that boracic acid, when locally applied to nerves. causes the part to lose the power of originating, but not of transmitting, im pulses; so that, if the galvanic current be applied to the part of the nerve which has been exposed to the drug, no mus cular contractions result; but, if the poles be placed above this part, the distal muscles respond at once (Wood). Some persons, however, appear to be able to bear with impunity almost fabulous doses of the drug, which evidences that its exact physiological status is undeter mined and chiefly a matter of specula tion.
In doses of 30 to GO grains often re peated, boracic acid is likely to induce nausea and vomiting, and, if persisted in (or even in large, single doses), to give rise to concatenation of symptoms in dicating gastro-enteritis.
Bruswanger (von Renterghem and Laura) remarked diuresis with increased desire to urinate to follow doses of from 30 to 120 grains; he believes that the acid is eliminated through the kidneys as an alkaline borate, in which conclu sion Rabuteau concurs. Polli, however, does not believe that the acid undergoes any alteration, but that it is passed un changed. H. C. Wood states that it is rapidly eliminated with the urine, and also escapes with the perspiration, saliva, and faeces. It increases elimination of urea, as well as the flow of urine.