TALBOT4460

[The envelope for this letter is in a private collection:]
H.F. Talbot Esq^r
Lacock Abbey
Chippenham
Wilts
31. Sackville Street
London

__________

Dear Sir,

M^r Collen ¹ has been so kind as to send me one of his Calotypes which has astonished me and all who have seen it.²

D^r Adamson ³ to whom I have just shewn it despairs of ever coming near it. I enclose you one of his ⁴ which is fixed by washing in water and then brushing it over with the Solution of Bromide of Potassium. He has tried every method and cannot fix the picture, that is the Positive one, as he could wish. - Experience has surmounted many of his difficulties, but defects in the best Paper which he can procure still disturb the uniformity of his Results. -

I am just working with a remarkable new salt the Cupreso-Cupro-Sulphate of Potash discovered by D^r Playfair. ⁵ It has a splendid Greenish Blue Colour. When heated, its water of crystallisation is driven off, & it becomes white. When melted it becomes almost black, & opaque. In Cooling it becomes yellowish (by transmitted light) then bright sap Green, then Yellowish & then white. When again melted it performs the same round of changes.

I am Dear Sir, Ever Most Faithfully yrs
D Brewster

S^t Leonards S^t Andrews
March 22^d 1842