That a material difference exists between the French and English practice of medicine, is universally known; and the compliment of superiority is seldom allowed to the former. Improvement, however, in the art of medicine, which the successful cultivation of chemistry and of morbid anatomy has so largely introduced in the last twenty years, is not confined to ourselves. The professors of chemistry at Paris receive their appointments and their conveniences from the government. That valuable commodity, time, is much at their command, because they confine their pursuits more than most of those who are engaged in teaching chemistry in London. The facility of procuring, at Paris, the examination of dead bodies is such as to favour the study of morbid anatomy most completely. The general objection amongst the French to the use of calomel prevails almost as strongly as at former periods; and certainly amounts to a prejudice. I learnt, on good authority, at Paris, that this medicine is usually found to act in a peculiar manner on the constitution of the French patient; as it commonly produces irritation in the intestinal canal to a degree that causes extreme discomfort. I need not relate with what freedom and satisfaction the English make use of this active medicine. I apprehend that the difference of operation is to be ascribed chiefly to the respective nature of the diet in the two countries. The remark applies most particularly to the free use of light wines, amongst the French. The vin ordinaire must produce very different effects from the English malt liquor; or the use of plain or soda water, in conjunction with wines of more sound quality. Indeed the difference of regimen appears to me a sufficient explanation. I may here remark how very materially the action of mercurial medicine on the bowels is controuled by suitable preparation of the patient with mild mucilaginous drinks. If, on the contrary, the stomach and intestinal canal be charged with acescent liquor, vinous, or of any other kind, acescent food, and fresh fruits, irritation and disorder, more or less painful, may be expected as almost a certain consequence. If the French employ calomel or other preparations of mercury too little, we doubtless run into the opposite error, of using them too much. It calls for the gravest censure, that, in almost every nursery, calomel should still be administered by the parent to young children and even infants, with as little consideration as if it were a simple domestic medicine. I am convinced that the infantile constitution is frequently most sensibly injured by so erroneous a practice, and that the scrophulous disposition, which might otherwise be dormant, is thus called into action at an early period of life. I think it ought to be an established rule, that mercurial medicine should not be administered to young children without the sanction of medical authority.