18 ON THE ACTION OE TRANSPARENT BODIES 



It acts less powerfully upon green light than sulphuric acid, 

 phosphoric acid and water. 



69. Rosemary, Oil of. 



This oil acts less powerfully upon green light than crown- 

 glass, and a very little more powerfully than flint-glass. 



70. Rosin. 



This substance acts less powerfully upon green light than 

 crown-glass and flint-glass. The secondary spectrum with 

 flint-glass, is fully as great as that produced by flint-glass oppo- 

 sed to crown-glass. 



Rosin acts a little less powerfully upon the green rays than 

 oil of cloves. 



71. Rue, Oil of. 



This oil acts more powerfully upon the green rays than 

 crown-glass, and a very little more powerfully than flint-glass. 



72. Sage, Oil of. 



This oil acts less powerfully upon green light than either 

 crown or flint glass. 



73. Sassafras, Oil of. 



This oil acts more powerfully upon green light than oil of 

 cassia, balsam of Tolu, and oil of anise-seeds, but less powerful- 

 ly than crown and flint glass, and oil of cloves. 



74. Savine, Oil of. 



This oil acts less powerfully upon the green rays than crown- 

 glass, and perhaps a little less powerfully than flint-glass; but 

 more powerfully than oil of spearmint, 



75.. Selenite. 



