29 



Ordinary Meeting, December 26th, 1860. 



Dr. R. Angus Smith, Vice-President, in the Chair. 



Ordinary Meeting, January 8th, 1861. 



E. W. BiNNEY, F.R.S., F.G.S., &c., Vice-President, 

 in the Chair. 



Mr. Ransome exhibited and explained the means of obtain- 

 ing a photograph, which, although appearing a confused series 

 of light and shade, yet, when reflected from a polished cylinder, 

 was a beautiful picture. 



Dr. Crace Calvert brought under the notice of the 

 Society an interesting communication made to him by Pro- 

 fessor Arnaudon, of Turin, to the effect that oxalate of 

 ammonia completely modifies the action of yellow prussiate of 

 potash when mixed in solution with a salt of peroxide of iron. 

 Thus, if oxalate of ammonia be added to this metallic salt, it 

 will give no prussian blue when a solution of yellow prussiate 

 of potash is added ; but on the addition of an acid, prussian 

 blue is immediately produced. The knowledge of this fact 

 may be interesting to calico printers, as it will give them the 

 means of easily producing prussian blue on their fabrics. To 

 attain this desirable end, the printer will simply have to pad 

 his fabric through a mixture of persalt of iron and oxalate of 

 ammonia, dry, and print an acid where he wishes to produce 

 the blue. 



After Dr. Calvert had made a few more remarks on this 

 subject, he stated that he had lately examined several varieties 

 Proceedings— Lit. & Phil. Society— No. 7.— Session, 1860-61. 



