It may be considered therefore that the properties of the seeds become sufficiently extracted in the stomach and intestinal canal, to excite the mucous membrane to increased secretion, and also to influence the action of the nerves. They are found principally useful to those invalids who suffer from general deficiency of secretion in the intestinal canal, and from nervous langour. I do not conceive that they are so proper for persons of the inflammatory diathesis, and who become easily heated; and I should rather approve of them as an occasional than a constant remedy, for they are not a certain aperient, and I do not think it desirable to subject the canal constantly to this kind of stimulus. If the seeds accumulate very much, some inconvenience may be occasioned by their augmentation of bulk, and if they be retained in the intestines, some further inconvenience may result from the disengagement of sulphuretted hydrogen. [6] M. Goupil, who was attached to the Hospital of Val-de-Grâce for two years, has given a clear view of these doctrines, in a work entitled Exposition des Principes de la Nouvelle Doctrine Médicale, &c. Paris, 1824. [7] With regard to many other medicines, the most useful maximum of dose is an interesting question. I am certain that the largest quantity which the stomach will receive, is not the most efficacious. The action between the medicine and the stomach must be mutual. If we take, for example, so innocent a medicine as the carbonate of iron, I expect more effect from the dose of a dram than half an ounce, which would incommode the powers of the stomach by its mass. The observation applies to all medicines which are of a very insoluble nature. I do not mean, in a general sense, that a small dose of a medicine has equal power with a large one, but that there is a point of increase, beyond which the efficacy becomes lessened. [8] Sulphate of quinine may be procured by digesting bruised bark in repeated portions of diluted sulphuric acid, until the liquor no longer possess a bitter taste. The different liquors are then to be mixed together and strained. To the strained liquid, lime is to be added, until the mixture assume a chocolate brown appearance, and a precipitate subside to the bottom of the vessel. This precipitate must be washed with a little cold water, dried, and digested in alcohol. The alcoholic solution, when submitted to distillation, leaves, in the retort, a brown viscous liquid, which is to be treated with a suitable quantity of boiling dilute sulphuric acid and a portion of charcoal. This solution is lastly to be filtered, and set aside to cool, when crystals of the sulphate of quinine will form. Mr. Garden informs me, that the largest portion of the sulphate of quinine which he has been able to prepare from the best yellow bark, is as one to fifty.