On the Action of Hydrofluoric Acid on Glass. 15 



variegated solution. The principal colour evident in such cases was 

 a deep green, but dark blue was also seen at rare intervals. 



The above observations were repeated several times, and always 

 with the same results, with the exception that the small particles of 

 glass floating in the drop of acid exploded now and then, causing 

 a great commotion in the hquid and throwing up little jets of finely- 

 divided acid, behaving as if the small glass particles were hollow 

 spheres, I may also mention that when these explosions occurred, 

 bright flashes of light were visible, resembling closely the appearance 

 of rainbows seen in waterfalls. 



VOL. VII. 



