An introduction to medical literature, including a system of practical nosology : intended as a guide to students, and an assistant to practitioners. Together with detached essays, on the study of physic, on classification, on chemical affinities, on animal chemistry, on the blood, on the medical effects of climates, on the circulation, and on palpitation / by Thomas Young.

Date:: 1823

Credit: An introduction to medical literature, including a system of practical nosology : intended as a guide to students, and an assistant to practitioners. Together with detached essays, on the study of physic, on classification, on chemical affinities, on animal chemistry, on the blood, on the medical effects of climates, on the circulation, and on palpitation / by Thomas Young. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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with the sulfuric acid, afford an empyreumatic vinegar; but this is the case with several fixed vegetable acids, which cannot therefore be considered as identical with the acetic. I have myself found that, in the formation of butter, air is absorbed, and not evolved, as some chemists maintain ; an event which could not occur in any other circumstances, than that the milk had been before in a state of fermenta- tion, and had been impregnated with carbonic acid. I have proved that the curd is held in a clear solution, and not merely suspended in the milk, and I have endeavoured to determine how far it differs from albumen, to which it has some resemblance, and to which Scheele compared it. I have further shown that milk contains no gelatin, but that the extractive substance, which gives a brown colour to sugar of milk, resembles in its composition that which is found in the juices of meat and in uriue, and consists of the lactic acid, together with lactated and muriated alkali, and .the extractive matter soluble in alcohol, which usually accom- panies these substances. [The lactate is only purified by being boiled with fresh lime, and digested for 24 hours with levigated carbonate of lead, which would decompose an acetate. Afh. III. 13.] I have examined most of the salts formed by the lactic acid, and I hope 1 have fully proved, that it cannot be either the acetic, or any other of the vege- table acids, but that it must be a peculiar and very remark- able acid, which is found not only iu milk, but, in equal or still greater quantities, iu other animal fluids; and I have restored to our immortal countryman Scheele the honour of never having advanced an incorrect statement, in any part of chemical science. [Since the milk coutaius three charac- teristic substances, totally different from each other, it is not improbable that each of these is afforded by its peculiar vessels : although in some cases the formation of heteroge- neous secretions may perhaps proceed collaterally, as in the chemical process for the formation of nitric ether, which is accompanied by that of the malic acid. Afh. III. 6.] By following the mode, which I have adopted, of viewing

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