80 MICROSCOPIC OBJECTS. 



lumns, serrated on each side, may be observed among the 

 cellular tissue of the husk : if another specimen (dry) be 

 burnt carefully between the glasses, and the ashes be 

 mounted in balsam, the sihceous columns will still be 

 seen. In the ashes of the husk of the wheat, rows of 

 concave discs may be observed, which are composed of 

 some metallic oxide. In the ashes of the calyx and 

 pollen of the mallow may be detected organized lime. 

 In the ashes of coal, a variety of vegetable structures, 

 as cellular tissue, spu-al vessels, &c., may be discovered; 

 and as these vary in the coals from different localities, 

 the place of an unknowTi specimen may be determined. 

 In these experiments it is necessary to render the ashes 

 transparent by immersion in balsam. 



Active Molecules. — If a drop or two of clear water be 

 placed upon a glass shde and a httle gamboge be rubbed 

 down in it, the particles will be observed in a constant 

 state of activity, even after the shde has been covered by 

 a thin slip of glass and sealed up for years. To observe 

 this motion a very high magnifjong power is necessary, 

 say 600 to 1000 diameters. A common single lens will 

 exhibit them very well. 



Bitu7ninous. — ^Tlie origin of coal has been a problem 

 with the geologist, the solution of which he has sought 

 for with anxious care. The microscope has at length 

 unravelled its history ; for its vegetable nature is clearly 

 discoverable through aU its transitions, from the wood to 

 the peat, lignite, jet, anthracite, and then to the perfect 

 bituminous coal. For successfully conducting these re- 



