LIGHT: REFLECTION 275 



light, and only see them by scattered reflection, may be shown 

 by the simple experiment represented in fig. 144. A confec- 

 tioner's glass jar A, about six inches diameter, is covered with 

 a flat glass plate B, after dropping in a bit of smoking brown 

 paper which has been dipped in a solution of saltpetre. The 

 plane-reflector c is adjusted to throw down the whole beam 

 from the lantern (either crossed from the objective as drawn, 

 or the parallel beam may be used). A cloudy light fills the 

 jar. Taking off the plate and blowing the smoke out, dark 



Fia. 144. Scattered Reflection 



spaces appear, showing that where no solid particles reflect 

 light to the eye, we see nothing. Or the jar may be filled 

 with clear water, which is also nearly invisible ; but on 

 stirring in a teaspoonful of milk, the same lambent light 

 illuminates the whole room. The black particles of soot> 

 equally with the white (or supposed to be white) particles of 

 milk, reflect white light. 



153. Law of Reflection. This is simply demonstrated with 

 the plane-mirror A B, arranged as in fig. 145 near the nozzle 



T2 



