SUMMARY OF CUKRENT RESEARCHES. 



Microstructure of Coal.*— J. Lomax describes and illustrates by 

 photomicrographs the structure of the different layers forming a typical 

 coal seam. Most coal seams were originated by a regular deposition' from 

 the growth of vegetation on the Bpot where they were now found. The 

 lower part of the seam consisted of a bed of very fine humus. Higher 

 up the seam were remains of Cordaitise, a type of plant belonging to 

 the Grymnosperms. Above these were Lycopods, which in the hj 

 layers became predominant. Higher still in the seam the plant-life 

 deteriorated, and the top layer resembled the bottom. It has been 

 shown that the alternating dull bands and bright bands in coal differ in 

 that the dull bands are more resinous. When coal is freed from the 

 normal pressure in a seam, the more resinous bands expand, while the 

 less resinous bands are cracked and pulled asunder by the unequal expan- 

 sion. This appears to be the chief cause of the disintegration of coal into 

 6lack and dust. 



* Iron and Coal Trades Rev., xc. (1915) pp. 46-48 (11 figs.). 



