WCP2934

[1]

Copy.

90 upper Tulse Hill. S.W.

31st, March. 1909.

Dear Prof. Meldola,

For a long time it was very doubtful if carbon exists in the sun, as the lines are very inconspicuous ones.

It is now certain that carbon is in the sun; but, in Wallace's¹ word, "whether as a gas of the pure element or only as a compound" it is rather a matter for chemists to decide.

The lines upon which its presence in the sun rests, are those of the banded spectrum of flames, about which there has been so much controversy. In 1868, when I discovered this spectrum in Comets, I made a good many laboratory experiments and came then to the conclusion that it was due to vapour of carbon. Since then a number of workers have come to different conclusions — a hydrocarbon; — or an oxide of carbon! (Smithells²). There is no doubt that the fluted character suggests compound molecules.

These bands are not only found dark in the solar absorption spectrum, but also, Hale has found them bright in the chromosphere. Hale calls it "carbon vapour". His words are: "a multitude of fine bright lines due to the vapour of carbon".

In addition to this spectrum there is also in the solar spectrum the spectrum of cyanogen and the strong lines on the ultra-violet, which in 1881, I discovered in the light of a comet.

Stokes thought that Smithells had settled the vapour controversy; but I do not think his conclusion is generally accepted. Those who were for a hydrocarbon, and those who were for pure carbon vapour, still adhere to their several opinions.

I am sorry to say that Lady Huggins³ has been very unwell [2] through a chill, she is much better, but still weak.

I hope that you and Mrs. Meldola have not suffered. so sorry to see the announcement of the death of Dr. Gamgee⁴.

Yours sincerely, | (signed) | William Huggins.