Though personally unknown to you, I take the liberty of addressing a few lines to you on the subject of your beautiful discovery of the Calotype. Sir David Brewster <1> some months ago sent you a Negative picture <2> which I made in the County of Wicklow and which you were kind enough to Positive for me. I have never been able to preserve the Positives without making them of a disagreeable red colour very unlike the beautiful lilac of your positive pictures. Will you be kind enough to let me know how you prepare and preserve your chloride pictures what strength of Nitrate of Silver solution and what strength of the preserving solution
I am Sir Your Obedient Servt
W. H. Furlong
H. F. Talbot Esqr
[The envelope for this letter is now in a private collection. It is addressed to Talbot at Lacock Abbey and Talbot wrote "Furlong" on the front. It is postmarked 16 March 1842, St Andrews.]
1. Sir David Brewster (1781-1868), Scottish scientist & journalist.