6 ON THE ACTION OF TRANSPARENT BODIES 
It exercises almost the same (perhaps a litile greater) action 
“upon green light, as oil of cloves. 
58. Nitrate of Potash. 
The refractive force which produces the greatest refraction 
in this salt, acts much less powerfully upon green light than - 
crown-glass, and a little less powerfully than flint-glass. 
59. Nut Oil. 
Nut oil acts less powerfully upon green light than crown- 
glass. 
When it acts in opposition to flint-glass, no secondary spec- 
trum is visible. 
It acts more powerfully upon green light than oil of marjo- 
ram. 
60. Nutmegs, Oil of. 
This oil acts less powerfully upon green light than crown- 
glass, and a very little less than ane Saat. 
61. Olives, Oil of. 
Oil of olives acts less powerfully upon the green rays than 
crown-glass, and a very little less than flint-glass. 
62. Pennyroyal, Oil of: 
This oil acts much less powerfully upon green light than 
crown-glass, and considerably less than flint-glass. 
63. Peppermint, Oil of. 
Oil of peppermint acts less powerfully upon the green rays 
than crown-glass, and a little less powerfully than flint-glass. 
64. Poppy, 
