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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the habit of considering them as perfectly dry, when they contain no more water than is necessary for their existence. Neither sulfuric, nitric, muriatic, fluoric, nor, as far as we yet know, any of the vegetable acids, can exist alone; but each of these acids, in its strongest or purest form, always contains a portion of water, which affords it the same quant- ity of oxygen as any other base with which it is saturated. These combinations may without impropriety be considered as salts of water, but since we are accustomed to distinguish those combinations only by the name of salts, of which the bases are so powerful, as to conceal the acids from our taste, and from other tests, this mode of representation is at first repugnant to our prejudices. Rem. Some acids contain also another portion of water, which serves for their crystallization, but which is less in- timately united with them, and may therefore be expelled by heat. Such are the oxalic, citric, and boracic acids ; and the two former can only be deprived of the whole of the water by presenting to them a stronger base. These cry- stallized acids are in fact analogous to crystallized salts. C. In its combinations with saline bases, water so far sup- plies the place of an acid, as its electricity is positive with respect to theirs : but being in itself rather of the nature of a base than of an acid, it combines in smaller proportions, containing, when united with potass, soda, barita, lime, magnesia, and alumina, only an equal quantity of oxygen with that of the base. Some few bases also, for instance, the oxyd of iron, combine with a quantity of water, of which the oxygen is only equal to half that of the oxyd. Rem. These combinations have long been called hydrates, from a correct idea of the nature of the combination. [But surely the term hydrate has not been confined to such cases, and has rather been used inadvertently for hydret, as an in- different kind of combination, analogous to sulfuret, and it may at least be questioned whether this denomination would not still be the safest.] The hydrates of potass, soda, barita, and strontian, do not lose their water by ignition ; from all 2 o 2

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