From Lyon Playfair   16 May /60

Edinburgh | 16 May /60

My dear Tyndall

I have been reading your own & others views on Regelation¹ & it has struck me that a good deal too much stress is put on Water & Ice being the same Chemical Body. I do not believe this to be so. Let me start with my assumption, Water according to my view is constituted on the type of Peroxide of Hydrogen

like Water,

The reason for this I need not enter into at present. Ice according to my fancy is

or a solid hydrate of the chemical body Water represented in its exact analogue Sulphuretted Hydrogen, peroxide of Barium, Hydrates of Chlorine, Sulphurous Acid & e.

Hydrate of Chlorine,Bra^e

Wöhlers Hydrate of HS. (probably).

Hydrate of Sulphurous Acid

Hydrate of Peroxide Barium

or Hydrate Barytes

Now this assumed Hydrate of Water constituted on its analogous solid hydrates, I further assume begins to be formed at the point of maximum density of Water, or rather just below it, but that it is held in solution by the Water which has not passed into that state.

Hence Water or rather the solution of Ice between 39.1 & 32°² expand because Ice is less dense than Water

Hence also its refraction angle increases as though it contracted, because the hydrate ice has a greater refractive angle than the body Water.

Hence also the solution of Ice may be cooled below 32° without freezing, just as a supersaturated solution of Sulphate of Soda can introduce a crystal of the Salt into the latter & of ice into the former & the crystals shoot out

+ .

If then there be any foundation in the assumption that Water between 39° & 32° is not simply Water but a solution of its solid Hydrate Ice, you will readily see an application to regelation, for anything that favours the crystallization of this dissolved Hydrate may produce junction at a temperature which according to the favourable conditions presented may be anywhere between 39° & 32°.

The first part of the letter involves a theory on which you could consult Frankland (to whom I have explained it) viz. that neutral salts & hydrates are constituted on the only neutral oxide which we know or & not on the highly basic protoxides the favourite type of the Young School.³ But I send the suggestion to you merely as one worth thinking of—as a speculation not a theory

Yours truly | Lyon Playfair

RI MS JT/1/P/122

RI MS JT/1/TYP3/992–3