My Dear Sir,

Having been some time in Edinr I have only now received yours of the 14^th. ^<1> Had I been at home I would have sent you the very pieces of Plate Glass with which I made my Exp^ts; but they would not have helped you in the least, as the Fringes are equally easily seen with plates of any thickness, and I cannot conceive where your difficulty lies. If you fix the one Plate on the other by two pieces of soft wax thus, and [illustration] press them so as to form a small angle with each other, you will scarcely fail to succeed, and by stopping the rays which are once, twice etc reflected you will observe easily the succession of phenomena wh^h I have described.

Your discovery of circular crystals ^<2> is most curious, and so far as I know entirely your own. You will oblige me much if you could send me a few placed in Canada balsam between two thin pieces of glass thus [illustration] which will preserve them for any length of time. I should like much also to see a specimen of the new Dichroitic crystals which you mention.

The new fluids which I discovered in crystals cannot possibly be any of the liquified gases in a pure state: because they contain a large quantity of solid matter which is left after evaporation.

I am in great haste Ever Most Faithfully yrs
D Brewster

Waterloo Hotel
Edin^r.
April 25^th 1836.

P.S. you would oblige me by sending the Enclosed to the Penny Post.

H.F. Talbot Esq^r.
31 Sackville Street ^<3>
London

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Notes:

1. Not traced.

2. See WHFT, ‘Observations on the Optical Phenomena of certain Crystals’, Philosophical Transactions of the Royal Society of London, v. 127, pt. 1 (1837); paper received 20 April, read 5 May 1836. [See Doc. No: 03305].

3. 31 Sackville Street, London residence of the Feildings, often used as a London base by WHFT.