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ELEMENTS OF MATERIA MEDICA.

Physiological Effects, (a.) On animals generally .—In one series ofexperiments, Dr. O’Shaughnessy (Lancet for 1831-2, vol. i. p. 369,)injected from 10 to 60 grains of chlorate of potash, dissolved in threeounces of tepid water, into the cervical vein of a dog: no ill effect wasobserved : the pulse rose in fulness and frequency, the urine was found ina short time to contain traces of the salt, and the blood of the trachealveins had a fine scarlet colour. In another series of experiments theanimal was stupified by hydrocyanic acid or hydrosulphuric acid gas :the brachial vein was opened, and a few drops of excessively dark bloodcould with difficulty be procured. Half a drachm of the chlorate dis-solved in water of the temperature of the blood was injected slowly intothe jugular vein : the pulsation of the heart almost immediately began toreturn, and in the course of eight minutes scarlet blood issued from thedivided brachial veins. In twenty minutes the animal was nearly reco-vered, and passed urine copiously, which was found to contain thechlorate.

(, b.) On man .—The action of this Salt on man requires further investi-gation. It appears to be refrigerant and diuretic, analogous to that ofnitrate of potash. Wohler and Steliberger have recognized chlorate ofpotash in the urine of patients to whom it had been exhibited, so that itdoes not appear to undergo any chemical change in its passage throughthe system. This fact is fatal to the hypothesis of the cllemico-physio-logists, who fancied that it gave oxygen to the system, and was, there-fore, well adapted for patients affected with scorbutic conditions, whichwere supposed to depend on a deficiency of this principle. Excessivedoses of the chlorate, like those of the nitrate, would probably produce anaffection of the nervous system; but I am not acquainted with any satis-factory case in proof. Ducliateu (Merat and De Lens, Diet . Mat. Med.)says that eighteen grains taken at thrice caused convulsions and delirium ;but the observation is probably erroneous: for others have not expe-rienced these effects, in much larger doses. Dr. Stevens (On the Blood,p. 155) says chlorate of potash gives a beautiful arterial colour to thevenous blood, and reddens the gums much faster than mercury.

Uses. —Chlorate of potash was originally employed as a medicine forsupplying oxygen to the system, where a deficiency of that principle wassupposed to exist. With this view it was successfully administered byDr. Garnett (Duncan’s Annals of Medicine, 1797) in a case of chronicscorbutus. Dr. Ferriar also tried it in scurvy with success (Med. Hist,and Reflect, vol. iii. p. 250). It was subsequently applied in the vene-real disease and liver complaints as a substitute for mercurials, whosebeneficial effects w'ere thought to depend on the oxygen which theycommunicated to the system (see the reports of Mr. Cruikshank andDr.Wittman, in Dr. Iloilo’s Cases of Diabetes Mellitus , 2d ed. pp. 504 and563 : also Dr. Chisholm’s letter in the same work, Preface, p. x). It hasalso been tried in cases of general debility, on account of its supposedtonic effects, but failed in the hands of Dr. Ferriar (op. cit.). In a case ofdropsy under the care of the latter gentleman it operated successfully asa diuretic. More recently, it has been used by Dr. Stevens (On theBlood, p. 296) and others, as a remedy for fever, cholera, and othermalignant diseases, which, he supposed, depend on a deficiency of salinematters in the blood, but as it was usually employed in conjunction withchloride of sodium (see the article on this salt, further on) and carbonate