Charles Giles Bridle Daubeny to Faraday   25 April 1826

Magdalen College Oxford | April 25th 1826

My dear Sir,

I have somewhere met with a statement as to the effects of compression on water which appeared to me of so anomalous a kind that I should be glad to learn whether there be any truth in it, and I know no one so well able (in such a subject more particularly) to give me information, as yourself. <->

The fact stated was, that when water expos’d to an high temperature underwent a certain quantum of pressure, as in one of Perkins’¹ Engines, it was resolv’d into its elements, or at least that Hydrogen was evolv’d. Now if such be the case, are we to imagine, that a still greater degree of pressure would compensate for a lower degree of temperature, and if that is the case, the bottom of the ocean must be compos’d of a mixture of the two elements of water, supporting a mass of that fluid. <-> The whimsical notion thrown out by Professor Leslie² in the supplement to the Encyclop. Britann.³ immediately suggests itself, but your researches would lead us to imagine that in all probability neither of the Elements of the water under such pressure would be in a gaseous state. <-> This circumstance however would not probably prevent the Oxygen from acting as a supporter of combustion, so that volcanoes might thus continue to burn under the sea without access to air - It is true that if the metals of the Earths & Alkalies are the cause of the volcanic action, water itself would act as a supporter, but even then we should have to account for the sulphurous Acid so commonly given off, the existence of which seems to imply the presence of Oxygen in an uncombin’d state. <-> Allow me, whilst on this subject, to ask your opinion on the mode in which I have attempted to explain the fact that Lavas of submarine origin appear to have evol’d more slowly than those which have flow’d in the open air<->

I account for this by the slow conducting power of liquids, and I contend, that the two causes which contribute to cool with such rapidity heated bodies thrown into shallow water, ought not to operate (to the same extent at least) at so great a depth. <-> The first of these, the change of the water into steam, could not probably take place at all; the second the expansion of the aqueous particles nearest the source of heat would be <<in some>> measure counteracted by the compress<<ion of>> the water itself at so great a depth. <-> I think it appears from Perkins’ experiments on the compressibility of water⁴, that if the ocean be 10 Miles deep, it would at the bottom be near 18 pr.ct. denser than at the top. Consequently if the expansion of water by heat follows the same ratio above 212° as it is found to do below, the lower stratum of the ocean would require to be rais’d nearly to 1000 of Fahrenheit, before it would acquire the same density as that at the surface estimated at 50° or 60°.- Ought not this circumstance to retard the calculation which would otherwise take place in the strata of water at the bottom of the ocean, when heat were applied. <->

I cannot ask you to devote much of your valuable time to the consideration of these, probably crude, speculations, but I shall be oblig’d by a line informing me whether the fact relating to the decomposition of water be correct or not, as I am preparing a work on Volcanoes in which I ought to allude to it⁵. - May I also ask you, whether you have ever examin’d a Quack Medicine sold by a Dr. Salamè⁶ an Italian Empiric, as I have been ask’d its composition, and should not wish to throw away my time in analysing it, unnecessarily. It is a brownish powder, soluble in water, & not affected by heat. This is all I know about it at present.

I take the opportunity of a friends hand to send you this letter which I hope you will not think too troublesome. I feel much oblig’d by your kind present of your interesting paper on Napthaline⁷ [sic] and remain

dear sir with much esteem | Yours truly | Charles Daubeny

Address: M. Faraday Esq | Royal Institution | Albemarle Street | London