The periodic law / by A.E. Garrett.

  • Garrett, A E.
Date:
1909
Catalogue details

Licence: In copyright

Credit: The periodic law / by A.E. Garrett. Source: Wellcome Collection.

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    other substances, and is therefore accepted as the atomic weight. As an example of this method, suppose it is required to find the atomic weight of oxygen, and the gases, SOo, CO2, and NgO are used. [It is to be understood that all the gaseous compounds containing the element should be examined, but these will be sufl&cient to illustrate the method.] When equal volumes of these gases and of hydrogen are weighed under precisely similar conditions of temperature and pressure, let the weights found for SO2, CO2, N2O, and hydrogen, be in the proportion 64 : 44 : 44 ; 2. Then, by analysis and synthesis of SO2, it is found that 50 per cent, of its weight consists of oxygen. Simi- larly, it is found that 72'7 per cent, of the weight of CO2 is oxygen, and 36‘3 per cent, of N2O by weight is also oxygen. Now 50 per cent, of 64 is 32, and 72-7 per cent, of 44 is also 32, while 36-3 per cent, of 44 is 16 nearly. 16 being the smallest number so obtained, is then taken as the atomic weight of oxygen. Many difficulties however stand in the way of deter- mining the atomic weights of the elements from their vapour densities. The gases must be of a homo- geneous nature, or errors will most surely occur. It was due to an error of this description that the presence in
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