6 ON THE ACTION OF TRANSPARENT BODIES 
acid may be regarded as exercising a greater action upon the 
green rays than the glass. 
When the nitrous acid acts in opposition to the muriatic acid, 
no uncorrected colour is perceived. 
8. Acid, Phosphoric. 
Phosphoric Acid acts very much more powerfully upon green 
light than flint-glass. The secondary spectrum is very vivid 
and beautiful. 
It acts much more powerfully upon green light than crown- 
glass. The secondary spectrum is very distinct. 
It acts much more powerfully upon green light than the mu- 
riatic acid. 
Its action upon green light is nearly as small as that of su/- 
phuric acid. By inclining the phosphoric acid prism, the uncor- 
rected green light appears towards its vertex ; but by inclining 
the sulphuric acid prism, it does not appear. Hence the phos- 
phoric acid acts a little more powerfully upon green light than 
the sulphuric acid. 
9. Acid, Phosphorous. 
Phosphorous Acid acts more powerfully upon green light 
than flint-glass, crown-glass, rock-crystal, or water. 
10. Acid, Prussic. 
Prussic Acid acts much more powerfully upon the green rays 
than flint-glass. 
It acts more powerfully upon the green rays than crown- 
glass. 
When it acts in opposition to blue topaz, no uncorrected co- 
Jour is visible. The refracting angle, however of the topaz 
prism, 
