20 ON THE ACTION OF TRANSPARENT BODIES 



81. Tartrate of Potash and Soda. 



This salt acts more powerfully upon green light than^mf- 

 glass, and does not appear to act very differently from crown- 

 glass. 



82. Thyme, Oil of. 



This oil acts less powerfully upon green light than flint 

 and crown glass, and oil of Juniper, but more powerfully than . 

 oil of cloves. 



83. Tolu, Balsam of. 



This balsam acts less powerfully upon the green rays than 

 oil of anise-seeds, oil of sassafras, and oil of lavender, and flint- 

 glass, but more powerfully than oil of cassia and sulphuret of 

 carbon. 



84. Topaz, Blue. 



This mineral acts more powerfully upon green light than 

 crown and flint glass, selenite, and leucite, but less powerfully 

 than water and rock-crystal. 



85. Tourmaline. 



This mineral acts more powerfully upon green light than 

 crown and flint glass. 



86. Turpentine, Oil of. 



This oil acts more powerfully upon the green rays than oil 

 of sassafras, oil of cloves, and Canada balsam, but less power- 

 fully than crown and flint glass. 



87. Water. 



