Processes employed in PJiotogenic Draiaing. 209 



An Account of the Processes employed in Photogenic Drawing, 

 i7i a Letter to Samuel H. Christie, Esq., Sec. R.S., 

 from H. Talbot, Esq., F.R.S.* 



Dear Sir, — In compliance with the request of several scien- 

 tific friends, who have been much interested with the account 

 of the art of Photogenic Drawing, which I had the honour of 

 presenting to the Royal Society on the 31st of last month, I 

 will endeavour to explain, as briefly as I can, but at the same 

 time without omitting any thing essential, the methods which 

 1 have hitherto employed for the production of these pictures. 



If this explanation, on my part, should have the effect of 

 drawing new inquirers into the field, and if any new discove- 

 ries of importance should be the result, as I anticipate, and 

 especially if any means should be discovered by which the 

 sensitiveness of the paper can be materially increased, I shall 

 be the first to rejoice at the success; and in the meanwhile, I 

 shall endeavour, as far as I may be able, to prosecute the in- 

 quiry myself. 



The subject naturally divides itself into two heads ; viz. the 

 preparation of the paper, and the means affixing the design. 



(1.) Preparation of the paper. — In order to" make what may 

 be called ordinary photogenic paper, I select, in the first place, 

 paper of a good firm quality and smooth surface. I do not 

 know thai any answers better than superfine writing paper. 

 I dip it into a weak solution of common salt, and wipe it dry, 

 by which the salt is uniformly distributed throughout its sub- 

 stance. I then spread a solution of nitrate of silver on one 

 surface only, and dry it at the fire. The solution should not 

 be saturated, but six or eight times diluted with water. When 

 dry, the paper is fit for use. 



I have found by experiment, that there is a certain propor- 

 tion between the quantity of salt and that of the solution of 

 silver, which answers best and gives the maximum effect. If 

 the strength of the salt is augmented beyond this point, the 

 effect diminishes, and, in certain cases, becomes exceedingly 

 small. 



This paper, if properly made, is very useful for all ordinary 

 photogenic purposes. For example, nothing can be more 

 perfect than the images it gives of leaves and flowers, especi- 

 ally with a summer sun : the light passing through the leaves 

 delineates every ramification of their nerves. 



Now, suppose we take a sheet of paper thus prepared, and 

 wash it with a saturated solution of salt, and then dry it. We 

 shall find (especially if the paper has been kept some weeks 



• riead before tlie Royal Society, Feb. 21, 1839. 

 Phil.Mag.a. 3. Vol. U. No. 88. Mar. 1839. P 



