Faraday to Charles Giles Bridle Daubeny   2 May 1826

Royal Institution | May. 2. 1826

Dear Sir

I do not recollect any such statement as that you mention respecting the decomposition of water at high temperatures and pressures independent of the chemical action of other substances present[.] Is it any thing about the experiments of Cagniard de la Tour¹ or Perkins² with his engine³ that has originated the idea in your mind? I should be very sceptical indeed of such an assertion and should require to see the experiments two or three times before I should believe it. I think all the probabilities are against it and that pressure would rather produce combination than destroy it. Indeed I have two or three facts or rather Mr Brande has confirmatory of the latter opinion. At the same time they are imperfect & do not bear directly on the point[.]

Going as in the second page of your letter to the notion that the oxygen & hydrogen are actually separated I do not see how it would facilitate explanations of combustions supposed to depend upon the presence of the free oxygen[.] I can imagine the oxygen leaving the hydrogen only because it from some cause or other is no longer in the relation of a supporter of combustion and if it be imagined to lose its power of combination with hydrogen I see no reason why it should retain its power of combination with sulphur: or in more general terms I think the relative situation of oxygen to the different combustibles under great pressure must be the same as at the earths surface[.]

With regard to your explanation of the appearances depending upon the different rates at which lava may have cooled in shallow & very deep water I go with you at once as to the effect produced in shallow water by evaporation and not produced in deep water but I do not see that the circulation should be diminished by the increase of density beneath - whatever the increase of density may be there can be little doubt that of two contiguous particles of water the one which is warmed more than the other will ascend and if it continues warmer than those it comes into contact with it must ultimately reach the surface for as it ascends it in consequence of being relieved from the pressure of the particles above which it had passed would expand and from its superior temperature would still retain a less specific gravity than the particle next above it[.] It seems to me that in an ocean of water even though the lower stratum should be several times more dense than the upper, that an appreciable increase of temperature at the bottom would immediately cause circulation ultimately extending throughout. I am of course speaking of those ranges of temperature not including the anomalous expansion of water below 40.°F

I have not see the Quack medicine.

I am dear Sir | Very Truly Yours | M. Faraday

Dr. Daubeny | &c &c &c

Address: Professor Daubeny | Magdalen College | Oxford