97 



of very frequent occurrence in the Calotype, and always occurs 

 when we use the io-gallic paper." 



" Parsonstown, 

 ''March 25, 1845. 

 «' Sib, — I am sorry I did not receive your letter before Dr. Robin- 

 son left this town, which I should have done, it being dated March 1 8 : 

 I did not get it until March 24. I will, however, forward it to him, 

 and I am sure he will, with his usual kindness, make whatever use 

 of it he thinks right. I will ask him to have it laid before the Aca- 

 demy with my Paper. I agree with the observations you make on 

 my Paper on general principles. There is no doubt at all that 

 your Calotype, Mr. Hunt's Energiatype, and my Catalysotype, if I 

 may be allowed, for the present, to call it so, are all pretty similar 

 in their modes of action, and perhaps they all come to the same point 

 in the end, — the decomposition of the salt of silver; but, as I said 

 in my former letter, if new modes of producing this effect were not 

 to be named, why call your process Calotype — why call Mr. Hunt's 

 Energiatype, &c., as they all agree in their general results with 

 the first experiments made with light on the nitrate of silver? Why 

 not regard them all merely as instances of the same general princi- 

 ple, and not isolate them, as it were, by designating each by a par- 

 ticular name ? You will say now that I agree with your ideas : I 

 always did. I think that cumbering science with a multiplicity of 

 hard names for every particular fact is very bad ; but the christen- 

 ing of my process has been forced on me by a similar line of con- 

 duct in others ; and when a nomenclature sufficiently good appears 

 (a task which I wish you would undertake), I will be the first to 

 blot out the word Catalysotype. 



" I do not pretend to any discovery; nor do I think my pro- 

 cess, in its chemical character, distinct from the general mass of 

 facts in active chemistry. I merely regard it as a new combination, 

 acting with great facility, very little complication, and, though not 

 involving a new principle, being developed without requiring any 

 second wash, which I looked on as characteristic until you men- 

 tioned the io-gallic paper, a process of which I was certainly igno- 

 rant before. You mention also Mr. Hunt's Energiatype as being 

 similar to mine ; but, as first published, it undoubtedly could have 



