420 Proceedings of the Society of Arts. 



ble Ink (617)^ and on the Writing Paper most proper to be used with 

 it, was read and approved. The Report is in the following terms : — 

 Report of Experimental Committee on Dr Traill's Indejible Ink : — 

 The Committee having met, and having heard the letter of Mr Ponton 

 read, and having reconsidered the Report of the Committee on Inks, and 

 also the experiments made by the Experimental Committee at last meet- 

 ing, with papers of various texture and surface, furnished by Mr Cowan, 

 beg to report, that the ink is indelible only on particular kinds of paper, 

 and are therefore of opinion, that the ink may be recommended as inde- 

 lible only when used with paper properly prepared for the purpose, and 

 tested. 



(Signed for the Committee) 

 John Scott Russell, Chairman. 



5. The Report of the original Committee on Dr Traill's and Dr Vcitch's 

 Indelible Inks, was read and approved. 



The following Candidates were admitted as Ordinary Mem- 

 bers, viz. : — 



1. E. J. Macbrair, Esq. S.S.C. 22 Duke Street ; 2. Henry Atwood, Esq. 

 63 Northumberland Street; 3. Mr George Duncan, Bootmaker to the 

 Queen, 55 Prince's Street ; 4. Mr William Smith, Merchant, 1 Blair 

 Street ; 5. Douglas Maclagan, M.D., F.R.C.S., 129 George Street. 



V)th April. — Sir John Graham Dalyell, Kt., President in 

 the Chair. The following communications were laid before 

 the Society. 



1. Biographical Notice of the late Mr William Blackie, optician. Up- 

 per Hermitage, Leith, with an account of the principal optical appara- 

 tus executed by him. Communicated by John Coldstream, M.D. Leith. 



Some of the lenses and other apparatus were exhibited. (622.) 

 Thanks voted to Dr Coldstream for the Memoir, and to Professor For- 

 bes, for exhibiting some of the lenses, prisms, &c. ; and the memoir was 

 ordered to be printed in the Transactions. 



2. On Photographic Etching. By Andrew Fyfe, M.D., F.R.S.E., VIcc- 

 Pres. Soc. Arts. (636.) 



Before proceeding to describe the Photographic Etching, Dr Fyfe stated 

 that, since last meeting of the Society, he had succeeded in preserving the 

 Photographic impressions done with the phosphate of silver, by immersing 

 them in a weak solution of ammonia in water, which, though it affected 

 the colour slightly, yet prevented the further action of the light. He 

 then made some remark? on the process of etching in the common way, 

 and afterwards on another mode of etching, by using a transparent var- 

 nish, by which he was enabled to take copies from engravings and of 



