WCP2933

[1]¹

CITY &GUILDS OF LONDON INSTITUTE

Technical College, Finsbury,

Leonard Street, City Road,

London, E.C.

March 30^th 1909

My dear Wallace,

I will answer your questions as far as I can — although (alas!) it is many years since I had anything to do with solar or stellar chemistry & with some of your queries I am by no means capable of dealing as an expert. But here goes: —

(1). With respect to the origin of solid mineral carbon there is no general view

— it is all hypothetical. Graphite is generally considered to be of vegetable origin, i.e. the extreme stage in the fossilization of coal. But it is known that graphite is also formed when solutions of carbon in molten metals (iron, &c.) cool down, so that some graphites may be of this nature. All terrestrial carbon may have been derived from gaseous carbon compounds — i.e. carbon dioxide, through plant synthesis. Diamond is generally considered to have crystallised from [a] molten metal solution of carbon very slowly & undery great pressure².

(2) The graphite in meteoric stones is generally considered to have been formed by the above method (molten metal solution) but there is no suggested hypothesis as to the origin of the carbon in meteorites. According to some astro-physicists carbon is present in large numbers of the "cooling" stars — the meteoric carbon may be of the same origin. If carbon is present in these stars of course it must be in a gaseous condition or it [2] could not have been detected by its spectrum.

(3) The carbon in the sun is I believe now considered to exist as vapour of the element itself, but there has been much controversy about this owing to ^the very great difficulty of distinguishing between carbon vapour as such & compounds of carbon (which are stable at very high temperatures) by spectroscopic methods. The me[l]ting point of carbon is given as about 3600°C. & it certainly has been converted into gas (i.e. vapour) in the electric furnace.

(As regards its condition in the sun I am writing to Huggins³ & will let you know his views).

I know of no book dealing with these questions generally. All our knowledge (real or speculative) is scattered. In his "Inorganic Evolution"⁴ Lockyer⁵ refers to carbon in the stars & Milky Way. If you want to see this book I will send it on.

I do not know "Stone’s Universal Portfolios". I only use Stolzenberg Portfolios

— which are nothing but strong card cases opening like a book.

We are going to Bournemouth for Easter & will try to pay you a visit.

Let me know if you would like to see Lockyer’s Book & I will send it on,

Yours very sincerely | R. Meldola⁶ [signature]