Dr. Draper's Note on the Tithonotype. 175 



bonaceous constituents of plants, all originally existed in and 

 passed through the green stage? It is the quality of radiant 

 matter to determine the position of atoms and the grouping 

 of molecules; and for this the sun, the great organizer, the 

 great life-giver, from age to age furnishes his unfading beams. 

 That analogies like this between the organic functions of 

 plants and animals in reality exist we might reasonably sup- 

 pose ; they are agreeable to the general plan of nature. 



Note on the Tithonotype. 



In the Number of this Journal for May last, I described a 

 process for obtaining tithonotypes, or copies of the surface 

 of Daguerreotypes by means of gelatine. 



A very important improvement on that process, an im- 

 provement which, indeed, has brought it almost at once to per- 

 fection, has been effected; — this is, to copy the surface in cop- 

 per by the Electrotype after it has been previously fixed by the 

 agency of a film of gold. 



Those who are conversant with these matters will see at 

 once that this is a very different thing from the abortive at- 

 tempts which were made early in the history of the Daguer- 

 reotype. Many artists endeavoured to transfer its surface by 

 precipitating copper upon it ; among others I made trials of 

 the kind. The results of those abortive attempts were mere 

 shadowy representations which could be seen in certain lights, 

 and which were very unsatisfactory in their effect*. 



The beautiful tithonotypes that are now so common in this 

 city are made in the following way : — The Daguerreotype is 

 carefully gilt by M. Fizeau's process, taking care that die 

 film of gold is neither too thick nor too thin. The proper 

 thickness is readily attained after a little practice. The plate 

 is then kept a day or two, so that it may become en filmed 

 with air. The back and edges being varnished, copper is to 

 be deposited upon it in the usual way, the process occupying 

 from twelve to twenty hours. If the plate has been properly 

 gilt, and the process conducted successfully, the tithonotype 

 readily splits off from the Daguerreotype. 



The reader will understand, that when the process succeeds 

 the Daguerreotype will be uninjured, and the Tithonotype a 

 perfect copy of it. If any portions are blue, or white, or 

 flesh-coloured, they will be seen in the same colours in the 

 tithonotype ; the intensity of light and shadow is also given 

 with accuracy, and indeed the copy is a perfect copy in all re- 

 spects of the original. A great advantage is also obtained 



* Professor Grove's voltaic process for etching Daguerreotypes, has, how- 

 ever, produced better results than those here alluded to by Dr. Draper. 

 See Phil. Mag.S.3. vol. xx. p. 18.— Edit. 



