TALBOT3811

44 Queen Ann S^{t 1}
Feb. 19. 1839

Dear Sir

I have made trial of the Ferrocyanate of Potash ² perhaps what I have obtained from the Chemists is not exactly of the same quality with yours; the following are the results I obtained this morning, how do they agree with yours?
1. simply dipping the design into this liquid, does not preserve it.
2. dipping, & then washing out with much water, only partially preserves, the design acquires an iron grey colour in sunshine.
3. if left in the liquid 2 hours, it is then preserved, but the ground changes from black to a rich yellowish brown–

I presume I have not yet used the proper method with this liquid.

I will now inform you of the 2 methods of fixing which I discovered & which I have very often employed with success; requesting you not to mention them just at present.

The first, is hydriodate of potash. This requires some nicety of management, because if too strong, it injures the ground; if properly managed it answers beautifully. The piece of lace I showed you at Slough ³ was preserved by this means, & has lasted five years – often exposed to the Sun –

But my usual plan, is to immerse the design into a strong solution of common salt. and not to wash it out. Exposed to sunshine this often acquires a light lilac tint; but if it is an object to secure perfect whiteness this may be attained by proper management.

Believe me Dear Sir Yours very truly
H.F. Talbot