1835.] Observations on Visible Vibration. 439 



\jfi inch B 

 2A „ B flat 



8. PYROLIGNEOUS ETHEE. 



Axis l^y inch. 



2\l inch G sharp, 



m „ G 



Vn »i A 2JJ „ F sharp 



Article V. 



On the accidental Colours of certain solutions on Mercury. 

 By Charles Tomlinson, Esq. 



To the Editor of the Records of General Science. 

 Dear Sir, 

 In the course of my experiments on Visible Vibration, I 

 noticed a ready and convenient method of observing acci- 

 dental colours without fatiguing the eye, which was new to 

 me, and will, I hope, prove interesting to some of the 

 readers of your Journal. 



Having occasion to diminish somewhat the reflecting 

 surface of mercury contained in a foot glass, I poured about 

 an ounce of a solution of litmus, which had become slightly 

 reddened by exposure to the air, upon the surface of the 

 mercury, when the upper portion of the glass above the fluid 

 was reflected twice, the lower reflection by the mercury and 

 the upper one by the litmus solution. On placing the fin- 

 ger on the periphery of the glass, and bringing one eye near 

 to another part of the periphery, two reflections of the fin- 

 ger were seen ; one the colour of the litmus, a beautiful 

 purple inclining to red, and the other a delicate light green 

 its accidental colour. 



On adding a few drops of nitric acid to the litmus solu- 

 tion, the accidental colour was of a dark and decided green. 



With mercury and a solution of chromate of potash a fine 

 blue accidental colour was obtained. 



