Biographical memoir of Sir Humphry Davy / [Georges Cuvier].

  • Georges Cuvier
Date:
1833]
Catalogue details

Licence: Public Domain Mark

Credit: Biographical memoir of Sir Humphry Davy / [Georges Cuvier]. Source: Wellcome Collection.

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    A single envelope of this metallic gauze, whenever employed with requisite precaution, henceforth secures miners from the terrible danger which threatened their lives; air ready for ex¬ plosion may surround their lamp without any other danger than that of extinguishing it, and even then, if there be sus¬ pended over the wick a spiral wire of platina, it will become in¬ candescent by the decomposition of the detonating gas, and af¬ ford light to the miner as long as there are any remains of re¬ spirable air. This instrument, now used in the greater number of mines, and introduced by Mr Davy himself into those of Hungary, has been the means of preserving the lives of many useful men : and its services would have been of even greater importance, had it not been for the indifference which has prevented its adoption in some countries, and negligence in observing the rules pre¬ scribed by its inventor in others. Men’s minds are usually so little occupied with the thoughts of death, that the most trifling present annoyance has more influence than the greatest danger when it appears somewhat remote. It now looked as if Mr Davy might be asked to make a dis¬ covery, adapted to the necessities of any particular ! case. The copper-sheathing of ships is oxidized by sea water, and in a nu¬ merous navy like that of England, the expense of renewing it is enormous. The Admiralty in 1823, asked him to suggest a preservative, and he was not long in complying with their wishes; he had only to refer to former discoveries to be enabled to add one more to their number. According to his practice, he first sought to give a precise account of the phenomena. Copper immersed in sea-water, pro¬ duces a bluish-green powder, on which is deposited the carbo¬ nate of soda, an obvious proof that the marine salt has been de¬ composed ; but, according to his theory of muriatic acid, this could not take place without oxygen, and as no hydrogen ap¬ peared, it could not be the water that furnished this oxygen but the atmospheric air which it contained. On the other hand, according to his theory of the correspondence between chemical action and the electrical condition of bodies, it was in conse¬ quence of its positive electricity relatively to the salts contained in the water, that the copper disengaged oxygen; it followed.
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