Nitro-Glycerin. A product obtained by treating Glycerin with equal parts of strong Nitric and Sulphuric Acids, successively added in small portions at a temperature kept below 32°. It is a yellowish oleaginous fluid, of a sweet, pungent taste, soluble in alcohol and ether, insoluble in water, slightly volatile and powerfully explosive. Chem. Form. C6H6 (2 NO4) O6.

Med Prop. and Jetton. Attention was first called to this substance in 1858, by Mr. Field, who stated that in very small doses (one drop diluted with 100 of rectified spirit), he found it in his own person to produce very marked and peculiar effects. " As a direct sedative of the nervous system," he remarks, "without possessing any stimulating or permanently depressing qualities, without affecting secretion, together with its power of subduing muscular action, it appeared to become an invaluable agent in the treatment of a large

* Mat Mod., vol ii. p. 72. L'Union Med , Jan. 31, 1860.

Nosograph Chir., t. i p. 184.

class of nervous and spasmodic diseases." He adds, that he has not met with one well-defined case of neuralgic or spasmodic disease in which it has failed to afford relief; and he suggests that with such a remedy we may look forward hopefully to the treatment of Tetanus, Hydrophobia, and allied affections. The subsequent trials with it by Drs. Fuller and Harley, while they show that Mr. Field had certainly overrated the powers of Glonoin, given in very small doses, leave little doubt that it is an agent of great power, capable in large doses of producing poisonous effects. Dr. J. B. Edwards* has shown that Glonoin has two distinct physiological actions, which are modified by the dose and the duration of its action. The primary effect of a small dose is that of a stimulant, which passes off in the course of half an hour; whilst in large doses (20 drops, administered to a full-grown rabbit), it induces a set of symptoms resembling, in a marked degree, those produced by strychnine, - tetanic convulsions, affecting violently the whole frame, contraction of the pupils, and exhaustion. It is evidently a remedy of great power, but its true therapeutic applications remain to be determined.