1879.] 



on Molecular Physics in High Vacua. 



151 



scries of colours — blue, apricot, red, yellowish green, orange, and 

 pale green. 



Next to the diamond the ru])y is one of the most remarkable 



Fk;. 10. 



Fig. 11. 



stones for phosphorescing. In tliis tube (Fig. 11) is a collection 

 of ruby pebbles, for the loan of which I am indebted to my friend 

 Mr. Blogg, of the firm of Blogg and Martin, who placed a small 

 sackful at my disposal. As soon as I turn on the induction spark 

 you will see these rubies shining with a brilliant rich red colour, as if 

 they were glowing hot. Now the ruby is nothing but crystallised 



