William Henry Fox Talbot to Faraday   Late March 1832

31 Sackville St | Wednesday

Dear Sir

I have been experimenting today with Mr Pearsall. After one or two little detonations of our oxygen, which we corrected by using alcohol mixed with water, we obtained a combustion apparently without light. But on removing the lamp into a dark room, we proved the existence of an internal flame, pointing downwards and touching the surface of the alcohol. Why this flame does not ignite the cotton wool I cannot tell. You had better therefore return on the paper I sent you, & I will send something else instead of it, for the Journal of the R. Inst.

I observed today rather a curious phenomenon which enables one to distinguish at once the Ammoniuret of Copper, from the Ammonio Nitrate of Nickel, both of which you have in the Laboratory. Both are blue by daylight & almost of the same tint, but look at a red hot coal thro the Nickel & you will see it Red, but thro' the Copper and you will see it blue¹.

Yours truly | H. F. Talbot

Endorsed by Faraday: Mar 1832.

Address: M. Faraday Esq. | Royal Institution | Albemarle St.