for the veratrum and the colchicum both owe their virtue

to the same alkaloïd - veratrine.

This potent remedy acts with extreme violence even in very minute doses, and its effects are most marked when applied to a mucous membrane. A small quantity put into the mouth excites most abundant salivation; if snuffed up into the nose, it causes sneezing of dangerous intensity; a quarter of a grain introduced into the intestinal canal produces abundant evacuations.

Magendie once gave two grains of veratrine, within four-and-twenty hours, to a patient without producing hypercatharsis; but then in this case the patient was a man who had had an apoplectic fit some time before. Magendie justly cites this as an instance of the way in which the effects of medicines are modified by the state of the nervous system; for he himself, having only tasted the potion which contained the two grains, experienced for several hours an insupportable acrimony in his mouth and pharynx, which was not quite gone on the following day the patient had not felt anything of the kind.

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An ointment made with four grains of veratrine to the ounce, may be employed externally in cases of tic douleureux or obstinate chronic rheumatism. It is a violent and unmanageable remedy in all its forms.

Prussic acid.

This most dangerous of all medicines was discovered by Scheele in 1780, but was first used by Professor Brera of Padua in 1809. It derives its name from having been originally made from Prussian blue; and, in like manner, its synonym hydrocyanic (acid) is derived from dwg, water, and xvavos, blue. A single

drop of pure Prussic acid is sufficient to kill a strong dog; but what is commonly called by that name is much diluted, sometimes containing only three per cent. of realacid. Even this, however, is dangerously and destructively powerful, requiring such caution in the prescriber and compounder as is not always to be found. Several of the French forms of Prussic acid are exceedingly strong, and it unfortunately happens that there is a syrup of hydrocyanic acid in the Parisian codex, (pharmacopoeia,) much stronger than one of the same name in common use. Some years since, seven epileptic patients, in one of the Parisian hospitals, lost their lives from this cause. Their physician had prescribed a moderate dose of the syrup, meaning the common one; but the attendant administered the syrup of the codex, and in three quarters of an hour the unhappy victims of a defective nomenclature were no more. It is to Prussic acid that bitter almonds, laurel leaves, peach blossoms, &c. &c. owe their poisonous qualities.

Iodine is an elementary substance, discovered by M. Courtois in 1813. It is obtained from the mother-water of kelp, but exists also in sponge and a great number of sea-weeds. Iodine is of a bluish-black colour, resembling bits of shining coal, with which it is said to be sometimes adulterated: this fraud may easily be detected, as iodine dissolves in alcohol, and is converted into vapour of a beautiful violet colour at a temperature of about 350° of Fahrenheit. It is upon this circumstance that its name is founded, which is derived from wons, of a violet colour. As burnt sponge, which contains iodine, was long known to be the best remedy in the treatment

of bronchocele (goitre), Dr. Coindet tried the effects of iodine in the same disease; and as these were very encouraging, and his testimony has been confirmed by that of innumerable practitioners, iodine continues to be the remedy most frequently employed in bronchocele. It is administered with great advantage in scrofula, and many disagreeable eruptions are cured by iodine with less expense of constitution than by mercury.

Iodine, by combining with hydrogen, forms hydriodic acid; and this again, by combining with potash, forms the hydriodate of potash, a milder remedy than iodine, and employed in larger doses in the same diseases.

Iodine alone will hardly dissolve in water, but its solution is easily accomplished by the assistance of the hydriodate of potash; the solution of the two combined forms the ioduretted hydriodate of potash, a useful medicine.

Like other good things, iodine has been abused, and especially by persons who have undertaken the management of their own cases. Thus Dr. Zinck tells us, that "As soon as it was known that the tincture of iodine would cure goitre, it was used at Lausanne in inconceivable quantities, to such an extent, that I may say without much exaggeration, that the phial of tincture of iodine took the place of the bon-bons box, for many carried it about with them. With a few exceptions, everybody used it, including those who were afraid that they might have the goitre; and the medicine was sold in the apothecaries' shops without a physician's prescription. I have reckoned up with M. Bischoff, an apothecary of our town, that we are quite within the mark if we estimate

at ten pounds' weight the iodine which he used in making the tincture which he sold the first year; and the other apothecaries sold it too. Many persons sent for it from Geneva, erroneously supposing that it would be better. This mania for taking iodine had its victims; but, as a general fact, we had but few in comparison with the great number of persons who used the tincture without any precaution; all those who sank under it had overdosed the remedy."

The quantity of iodine stated in the above quotation to have been used by Bischoff the pharmacien, is very great; for ten pounds are seventy thousand grains, and a grain is a common dose, and perhaps more than a proper one.

The combinations of iodine with lime, iron, arsenic, barytes, zinc, sulphur, and mercury, have been medicinally used, but can hardly be considered as established remedies.

Bromine has many analogies with iodine, and like it exists in many marine substances. It has been found in mother-water of salt-pits, in sea-water, in the waters of a great number of springs, and in sea animals and vegetables.

We do not know that any one uses bromine in this country. Magendie says that he employs it when iodine seems not sufficiently active, or when patients have become accustomed to its action.

Chlorine takes its name from its colour, for it is derived from xλwpos, green; it is a greenish-yellow gas of a pungent taste and smell. Its specific gravity is 2-4216. It was discovered by Scheele in 1774; but

Sir Humphry Davy first showed that it was an elementary body. This gas, diluted with water, has been administered internally in scarlet and typhus fever, and, mingled with the steam of hot water, has been inhaled in phthisis and other diseases. The late Mr. Thackrah of Leeds, who wrote so ably on the diseases of workmen, tried this expedient in the bronchitis, to which flaxmen are peculiarly subject. (Bronchitis means inflammation of the bronchi, the ramifications of the windpipe.)

"The inhalation of chlorine gas we have tried rather extensively among the workers in flax, suffering from chronic bronchitis. Sixteen of these men I induced to come every evening, after the day's work, to an apartment, the atmosphere of which we impregnated with chlorine, by pouring muriatic acid on manganese. Here they remained at first for a quarter of an hour, and afterwards for about an hour. One individual declared, the second evening, that he had not slept so soundly for several years as he did the night after inhaling; and, on the fifth evening, all the men declared their breathing freer, and the cough considerably reduced. Those who previously could obtain little unbroken sleep, had better nights; and others had regained appetite. The plan, from accidental circumstances, was omitted for three evenings, a recurrence of cough and dyspnoea was the speedy result; they gladly, therefore, returned to the inhalation of the chlorine, and continued it for several weeks with the most marked advantage. They have since resolved, on the approach of next winter, to take a room to themselves, adjoining their mill or houses, for the purpose of the regular inhalation of chlorine. Two