The decomposition of the fixed alkalies and alkaline earths / H. Davy.

  • Davy, Humphry, Sir, 1778-1829.
Date:
1902
Catalogue details

Licence: In copyright

Credit: The decomposition of the fixed alkalies and alkaline earths / H. Davy. Source: Wellcome Collection.

    18/60 (page 14)
    be easily made to run into one. At 50° Fahrenheit it becomes a soft and malleable solid, which has the lustre of polished silver; and at about the freezing point of water it becomes harder and brittle, and when broken in fragments, exhibits a crystallized texture, which in the microscope seems composed of beautiful facets of a per- fect whiteness and high metallic splendour. To be converted into vapour, it requires a temperature approaching that of the red heat; and when the experi- ment is conducted under proper circumstances, it is found unaltered after distillation. It is a perfect conductor of electricity. When a spark from the Voltaic battery of 100 of 6 inches is taken upon a large globule in the atmosphere, the light is green, and combustion takes place at the point of contact only. When a small globule is used, it is completely dissipated with explosion accompanied by a most vivid flame, into alkaline fumes. It is an excellent conductor of heat. Resembling the metals in all these sensible properties, it is however remarkably different from any of them in specific gravity; I found that it rose to the surface of naphtha distilled from petroleum, and of which the specific gravity was .861 and it did not sink in double distilled naphtha, the specific gravity of which was about .770, that of water being considered as i. The small quantities in which it is produced by the highest electrical powers, rendered it very difficult to determine this quality with minute precision. I endeavoured to gain approxi- mations on the subject by comparing the weights of per- fectly equal globules of the basis of potash and mercury. I used the very delicate balance of the Royal Institution, which when loaded with the quantities I employed, and of which the mercury never exceeded ten grains, is sensible at least to the of a grain Taking the mean of 4