20th. March 1857
My dear Sir
I intend to subject some of the questions which you have proposed1 to me to a very searching examination. Hitherto my attention has been directed to the change of form which a glacier undergoes, and I find that change, taking glacial ice as it actually is, to be accounted for by the incessant fracture—sometimes between very minute masses—and regelation of its parts. I am now working on the physical properties of ice and shall deal fully with those points to which you refer. With regard to the supposition of internal coldness the following fact may have some value. Suppose two flat pieces of ice at 32° to be placed together, with a moist film of the thinnest gold leaf between them, the film will, after a time, attain the temperature of the interior of the mass, which will equalize itself by what you call the conduction of cold, if cold exist, and the film will finally be frozen up between the two pieces. But this is never observed: the thinnest film of a good conductor which interrupts the contact of the ice masses themselves completely prevents their regelation. If you suspend a crystal of alum2 in a dilute solution of the salt, as the concentration increases by evaporation the alum will deposit itself on the crystal which will continue to grow while not a particle of the salt is deposited on the sides of the containing vessel. Does not this indicate a special attraction on the part of the crystal for particles of its own kind?, and may not this attraction, in the case of ice, be augmented by the juxtaposition of the two surfaces? I merely throw out these as conjectures at present, but before a year rolls over I hope to be able to give you a more satisfactory account both of the properties of ice and of the further bearing of those properties upon glacial phenomena. I wish I dare ask you to invent a term for me which would include the idea of fracture & renewal to which I believe the bendings of the glaciers are due. I have not seen Wedgewood’s3 paper,4 but will look for it.
I remain dear Sir | very faithfully yours | John Tyndall
RS HS 17.387
RI MS JT/1/TYP/2/504
questions which you have proposed: see letter 1356.
alum: an astringent mineral salt, typically occurring as colourless or whitish crystals, that is used as a mordant for dyeing, in tanning, for sizing paper and fireproofing materials, in water purification, and in medicine (OED).
Wedgewood’s: Josiah Wedgwood; see letter 1356, n. 5.
paper: see letter 1356, n. 6.
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