With some persons, however, the first dose of a quarter of a grain produces active sickness. It appears to me probable that the maximum of usefulness[7] is to be found in a moderate range of doses; and that it is desirable to avoid trying how much the stomach and the constitution will possibly bear. Have we a security that the accumulation of a very large quantity might not produce violent effects? Indeed, I am informed of an instance in which the amount of sixty grains was taken in divided doses in a short time; the direction being given that the medicine should be repeated till vomiting was produced. At length, such severe sickness did take place, as could not be restrained for many weeks. In the treatment of active inflammation, I have usually joined nitre in moderate doses, with tartarized antimony, in a saline draught; and when the inflammatory action has so far yielded, that I have had confidence in not requiring the further use of the lancet, and therefore not apprehended the inconvenience to which I have adverted at page 27, of disguising the disease, I have added digitalis to the draught occasionally; thus obtaining a combination of sedative medicines of great efficacy; and, according to my experience, not disagreeing with the stomach during the active state of the disease. We must always keep in mind that the effect of medicine is in the greatest degree relative to the particular disease for which it is administered, and to the force of such disease. The doses of active medicines are to be diminished as symptoms abate. In the case of a gentleman suffering from enlargement of the liver, and with whom mercury in any form acted very unfavourably, I obtained the most satisfactory results from the use of tartar emetic as an alterative; this medicine never occasioning that nervous irritation which invariably attended the use either of calomel or the pilula hydrargyri. The practice which I have here related, of administering large doses of tartar emetic, and that recommended by Dr. Hamilton, of the free use of purgatives, appear very opposite to the doctrines of Broussais, which inculcate such a tender regard to the susceptibility of the stomach and intestinal canal, as almost to discountenance the use of emetics and purgatives, from the apprehension of producing _gastrite_, or _gastro-enterite_. We are greatly indebted to the ingenuity and industry of the French chemists for many important results in vegetable chemistry; and as the most valuable of all the discoveries made, I may mention the separation of the essential principle of the yellow bark (cinchona cordifolia) called _quinine_; which, for medical use, is afterwards combined with sulphuric acid, forming the now well-known medicine, sulphate of quinine[8].