The new chemistry / by Josiah P. Cooke, Jr.

  • Josiah P. Cooke
Date:
1876
Catalogue details

Licence: Public Domain Mark

Credit: The new chemistry / by Josiah P. Cooke, Jr. Source: Wellcome Collection.

    103/376 page 97
    WEIGHT THE MEASURE OP MATERIAL. exact weight of the cliarcoal consumed. In the first two cases, the proof of the composition is analytical, in the third synthetical. In many cases we have both modes of proof. Thus, we can decompose water into oxygen and hydrogen gases, and show that the weight of the products is exactly the same as that of the water which has disappeared. We can also combine hydro- gen with oxygen, and show that the weight of water formed is exactly equal to that of the two gases con- sumed. Notice the important part which the weight of the substances concerned in our processes plays in this reasoning. That water consists of oxygen and hydrogen, and of nothing else, is a conclusion based on the fact that the weight of the substance has been found equal to that of its assumed constituents. Of course the reasoning implies the truth of the principle that in- crease of weight always indicates increase of material, and diminution of weight diminution of material, or, in other words, that the weight of a body is propor- tional to the amount of material it contains. But this principle, so obvious now, is by no means, as might at first appear, self-evident, and it is only comparatively recently that it has become an accepted principle of science. It was never fully enunciated before Kew- ton, and, although his master-mind was able to estab- lish the foundations of astronomy on this basis two centuries ago, it is only comparatively recently that the principle has been fully accepted in chemistry. For years after Newton, the chemists believed univer- sally in a kind of matter called phlogiston, which not only could be removed from a substance without dimin- ishing its weight, but whose subtraction actually added to the weight. It is the great merit of Lavoisier that G 2
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