1895 THE MICROSCOPE. 63 



When ready for examination, the charcoal should be allowed 

 to settle, and repeatedly washed with pure water before remov- 

 ing it from the tube. It should then be examined in water, 

 with powers of from 50 to 500 diamaters and may then be dried 

 and mounted in balsam. Some refractory specimens require 

 alternate washing and boiling in nitric and hydrochloric acids 

 before their structures can be made out. The process here indi- 

 cated does not produce a siliceous skeleton of the coal, but re- 

 moves the bituminous matter which is oxidized and dissolved 

 by the acid, and the mineral matters especially the sulphuret of 

 iron, which is one of the principal causes of the brittleness and 

 opacity of the crude mineral charcoal. 



Mineral charcoal is also known as fibrous coal, fossil coal, 

 mother-of-coal and is a soft black substance resembling charcoal 

 in appearance found in connection with coal, usually along its 

 planes of stratification or lamination in which the woody char- 

 acter of the material from which the coal was formed is more 

 perfectly preserved than it is in the body of the coal itself. 



In Dana's Manual of Geology it is said that even solid 

 anthracite has been made to divulge its vegetable tissues. 



Another method of examining coal is to grind the coal to a 

 fine powder and examine the fragments. Only the finest powder 

 will show structure. This plan is unsatisfactory. 



Another method is to burn the coal to a white ash and ex- 

 amine it under the microscope. This ash often exhibits perfect 

 skeletons of vegetable cells, but these are fragile and require 

 great care in their management. They should be first soaked 

 in turpentine and then mounted in Canada balsam. 



Section of Water Lily. — A section of the stem of the water 

 lily (Nuphar Advena) double stained, will make one of the pet 

 slides of a cabinet. 



The section cut near the joint or across the petioles makes 

 the prettiest mounts, as they are composed of different kinds 

 of cells, the usual parenchyma and of stellate cells, each of which 

 will take a different stain. When well cut and properly stained 

 they will make a slide of which any microscopist may be proud. 



Beal's Carmine Staining Fluid. — The following formula 

 will be useful : 



Carmine 10 grains. 



