Physiological essays on the action of poisons, and on the introduction of saline substances into the veins / by James Blake.

  • Blake, James, 1814-1893.
Date:
[1838-1841]
Catalogue details

Licence: Public Domain Mark

Credit: Physiological essays on the action of poisons, and on the introduction of saline substances into the veins / by James Blake. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    the axillary artery, so as to pass into the aorta. Under these cir- cumstances, a space of time, varying from thirty-five to forty-five seconds, has been found to elapse between the introduction of the substance and the cessation of heart’s action. I would remark, however, that all those substances which act in this manner on the heart also possess the property of impeding the passage of the blood through the capillaries for a time varying from fifteen to twenty-five seconds, so that these experiments furnish no exact in- dication of the time in which a substance which does not possess this property may pass between the points above alluded to. From those experiments in which the phenomena would be ob- served with the greatest accuracy, I conclude, that the time re- quired for a substance which does not act on the capillary tissue, to pass from any part of the vascular system back to the same point again, varies in dogs from twelve seconds to twenty seconds. These conclusions are in perfect accordance with those arrived at by Hering from a series of carefully conducted experiments on horses, in which he found that the whole round of the circulation was completed in about twenty-five seconds. Having now the requisite date by which to determine the time in which a substance can be circulated over the body, I shall pro- ceed to relate some experiments which have been performed with a view of discovering if a sufficient interval elapses between the application of those poisons which have been shown to act on the nervous system, and the first symptom of their effects, to allow them to be brought into contact with the nervous tissue through- out the body. Experiments have been tried with concentrated hydrocyanic acid, woorara, nicotine, conia, and strychnia,—poi- sons which have been shown to produce the most rapid effects on the animal economy. (Exp. 7.) Half a drachm of concentrated hydrocyanic acid was prepared by passing sulphuretted hydrogen over the bicyanide of mercury. The gas being previously dried by passing it over chloride of calcium, the acid was collected in a receiver surround- ed by a freezing mixture. It was used immediately after its pre- paration. In order to insure a marked effect being produced, the whole of the acid was poured, on the tongue of a strong dog, weigh- ing about eighteen pounds, the head being kept elevated. Eleven seconds elapsed between the application of the poison and the ap- pearance of any morbid symptom. The respiration then became affected. The animal was dead thirty-three seconds after the ad- ministration of the poison. If a tube be introduced into the trachea, through which the animal can breathe, a longer interval elapses between the application of the poison and the appearance of its effects. This is probably owing to the acid not being in- haled with the breath ; for on account of the extreme volatility of