In whatever form hemlock is administered, it will be necessary, in order to maintain a given effect, to increase the dose more rapidly than is requisite with most other narcotics; and there is scarcely any extent to which it may not be carried in this way with impunity; as, from its want of stimulant or corrosive properties, there is no danger of its exhausting the excitability of the system, or causing serious organic mischief. But one caution is here peculiarly important; namely, when it becomes necessary, during the use of these large doses, to change the parcel of the medicine, never to use the new parcel so freely as the one last employed, lest it might prove to be much stronger, and thus endanger serious results. The medicine is used in the form of powder, extract, tincture, and preserved juice, and in that also of its isolated active principle.

1. The powdered leaves may be directed, in the commencing dose of three or four grains, twice or three times a day, to be gradually increased until some effect is produced; such as a little giddiness, headache, nausea, or feeling of muscular weakness. in this form, however, the medicine is often nearly if not quite inert, and is at present not much used.

2. The Extract of Hemlock (Extractum Conii, U. S., Br.) is probably the form most employed. it is the inspissated juice of the fresh plant, and, if made with due care, is an excellent preparation. Too frequently the juice is inspissated by boiling, which impairs its virtues, and probably sometimes quite destroys them; so that the extract is not un-frequently very feeble, and often quite disappoints the expectations of the prescriber. When prepared by evaporation in vacuo, at a low temperature, it retains the virtues of the plant to a considerable extent. Another source of its feebleness is the influence of time and exposure, by which it is deteriorated. The best criterion of its efficiency is the development of the characteristic odour, like that of mice, when it is rubbed with solution of potassa. if it have none of this, it may be considered inert, and its strength will be in the proportion of that of the odour. When of very good quality, it gives rise almost to a feeling of the ludicrous, by the strength of the newly developed smell, and its associations. As now supplied to our markets, from our own factories, it is in general much superior to that formerly kept in the shops. The doses of hemlock are usually given at too long intervals. I find that not longer than four hours should, as a general rule, intervene, if it be desired to sustain a constant impression; and a still shorter interval would often be preferable. Two grains may be given at first, and rapidly increased, if necessary, until the point is reached at which it will produce some effect. it may be administered in pill or solution; but the former is usually preferred. The extract has also been used for inhalation in the form of spray; from one to three grains being dissolved in a fluidounce of distilled water. it has been administered in this way in asthma, and in irritative cough, whether laryngeal or bronchial.

A cataplasm for external use may be made from the extract, by reducing it to a semifluid state with water, and then spreading it over the surface of an emollient poultice, as of flaxseed meal, or bread and milk. From two drachms to an ounce may be employed, according to the size of the cataplasm wanted. in this shape it may be applied to tumours and ulcers, and to the surface of the body over internal affections; but, when it is brought into contact with abraded surfaces, the liability to absorption must be borne in mind, and directions left for the removal of the application should unpleasant symptoms occur.

An ointment may also be made from the extract by rubbing it with three or four times its weight of lard. This may be employed as a dressing for painful ulcers, or an application to irritated piles.

3. An Alcoholic Extract (Extractum Conii Alcoholicum, U. S.) is directed by our national code to be prepared by evaporating a tincture of the leaves. its strength, of course, will depend on that of the leaves, and it cannot, therefore, be relied on. The dose is the same as that of the ordinary extract.

The alcoholic extract of the seeds, collected before maturity, is said to be a good and stable preparation; but it is not directed by the Pharmacopoeia.

4. A Fluid Extract of Hemlock (Extractum Conii Fluidum, U. S.) was newly introduced into the U. S. Pharmacopoeia at the late revision. it is a concentrated tincture of the leaves, with the addition of acetic acid, which not only aids in the extraction of the active matter, but contributes to its preservation. A fluidounce is equivalent to a troyounce of the leaves. The dose to begin with is four or five minims, and this quantity or more may be added to a fluidounce of water, for inhalation by means of the atomizer.

5. A Hemlock Poultice (Cataplasma Conii, Br.) is directed in the British Pharmacopoeia to be prepared by mixing together an ounce of the leaves in powder, three ounces of flaxseed-meal, and ten fluidounces of boiling water. it may be used for the same purposes as the cataplasm prepared from the extract, above referred to, especially in painful ulcers.

6. A Tincture of Hemlock (Tinctura Conii, U. S.) is officinal. Being prepared, according to the U. S. Pharmacopoeia, from the dried leaves, it is liable to all the objections which apply to the leaves themselves. its goodness may be measured by the strength of the peculiar odour it emits, when a little of it is rubbed with potassa. The dose is from 30 minims to a fluidrachm.

From experiments recently made in England it is inferrible that the tincture of the leaves is either very nearly inert, or that it differs much as prepared from the product of different plants. Dr. Garrod exhibited repeated doses of from three to five fluidrachms three times a day without observable effect, and succeeded no better subsequently even with a fluidounce. (Pharm. Journ. and Trans., Jan. 1867, p. 382-3.)

7. The Tincture of the Fruit (Tinctura Conii Fructus, Br.) of the British Pharmacopoeia, being prepared from the fruit, is probably more efficient. it may, however, be given in the same dose.

As to the strength of this tincture there is some difference of opinion with English therapeutists. Dr. Garrod, whose failure to obtain any observable effect even from a fluidounce of the tincture of the leaves, found five fluidrachms of the tincture of the fruit to cause giddiness and a feeling of weight over the forehead; and, by a dose of six fluidrachms, produced a sensation as of a mist before the eyes, twenty minutes after each dose. On the contrary, Dr. John Harley took two fluidounces of a tincture of the fruit carefully prepared, without any other effect than such as might have resulted from the alcohol of the tincture. (ibid., p. 414.) Now as conium certainly has some degree of activity, and as its active principle conia is soluble in alcohol, and must, therefore, be contained in the tincture, the inference is either that Dr. Harley experimented with a preparation made from plants defective in power, or that alcohol has the power of completely neutralizing the effects of conia; and, if the view taken in this work of the respective character of these two narcotics, the one being a powerful stimulant to the cerebral centres, and the other a rather feeble sedative to the same parts, be correct, the latter branch of the alternative may be considered as highly probable; namely, that alcohol given with conium, in certain proportions, neutralizes its effect.

8. The Juice of Hemlock (Succus Conii, Br.) is a preparation of the British Pharmacopoeia, in which the expressed juice is mixed with one-third of its measure of rectified spirit, and is strained after standing. The dose is from thirty to ninety minims.