TALBOT3821

44 Queen Ann S^{t 1}
Feb. 27^th

Dear Sir

Will you allow me to communicate to M. Biot, ² who will of course mention it to the Académie des Sciences, your two beautiful methods of fixing or washing out, by the hyposulphite & the ferrocyanate? ³

With respect to the former, I should also wish to add a reference to the work in which you first described the hyposulphuric acid, ⁴ which I do not exactly know where to find–

Believe me Yours most truly
H. F. Talbot

Sir J. Herschel Bar^t
Slough