Volume 1

A system of chemistry / by John Murray.

  • Murray, J. (John), -1820.
Date:
1819
Catalogue details

Licence: Public Domain Mark

Credit: A system of chemistry / by John Murray. Source: Wellcome Collection.

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

    137/686 (page 119)
    This is illustrated in the solution of a salt in water. Any quantity of the salt, up to a certain quantity of it, may be combined with the water with equal facility j but after a certain portion is added, the combination ceases to pro- ceed, the mutual attraction is no longer exerted with ef- fect, and if any more salt be added it remains undissol- ved. The limitation to the combination in this case is named Saturation, and when the water has dissolved the largest quantity of the salt which it can dissolve, it is said to be saturated with it. 3^7, Combination is in some cases so strictly limited, that it takes place only in one proportion: in whatever other re- lative quantities two bodies may be presented to each other, they unite in this precise proportion, and any excess cither of the one or of the other remains uncombined. Water affords an example of a combination of this kind ; its constituent elements are combined in a proportion per- fectly determinate, that of 87.5 by weight of the one, to 12.5 of the other, and they can be united in no other proportion than this. Lastlj’^, Attraction is exerted between many bodies in such a manner that they may be combined in two, three, or four different proportions, but each of these is perfect- ly determinate, and they are capable of combining in no proportions different from these. Sulphur and oxygen combine in the proportion of 50 of the one to 50 of the other : they also combine in the proportion of 40 of sul- phur and 60 of oxygen. But they cannot be combined in any other proportions ; and if presented to each other in different quantities, and placed under the circum- stances which are favourable to the exertion of chemical attraction, they always unite in one or other of these pro- portions. There are many similar examples. It is chief- ly where attraction is exerted between bodies with much strength, that combinations in definite proportions are established, and that the peculiar laws regulating these