WCP2767

[1]¹

38. Parolles Road.

Upper Holloway

London. N.

July 24/98

Alfred Russel Wallace. Esq —

Sir,

As a highly interested reader of your latest book "The Wonderful Century",² may I venture to address a few remarks by way of criticism on a portion of one chapter — viz\ that on "the importance of dust" — Chap. IX.

While I do not wish to cast any doubt on the accuracy [2] of the general conclusions of Prof. Tyndall³ & other eminent physicists as to the influence of dust in the air as modifying the colour of sunlight as it passes through a smaller or greater volume of it, I think it wa ^is well to bear in mind a fact clearly brought out (I think) by the recent researches of Prof. [illeg.] These prove that liquid air (& therefore surely gaseous air) is not colourless but has a most decided blue or greenish-blue tint, even when viewed (as I have viewed it myself at the Royal Institution) in [3] comparatively small quantities.

One is forced then to conclude, that whatever part dust may play in the atmosphere (& that of acting as nuclei of condensation for water-vapor is certainly one), that pure air has in colour per se. I should think myself that this was also true of sea-water, or even of pure distilled water, though further experiments in this matter are very desirable.

Apologizing for thus introducing myself.

I have the honour to remain, | Your obedient servant | Henry Garnett⁴ [signature]

P.T.O

[4] P.S. On p. 89 I note among the list of coal-tar derivatives "artificial quinine". May I venture to state that quinine has never yet been synthesized, though possibly one or other of the new synthetic remedies (of the antipyrin class) has been termed "artificial quinine" — or "quinine substitute".

H. G.

Hy Garnett⁵