143 



Sections of Coal. 

 By J. Slade. 



(Read October 28th, 1870.J 



The origin of coal has ever been a subject of great interest to the 

 naturalist ; but so far as the microscope has been concerned in the 

 investigation, no satisfactory progress has been made until quite 

 recently. 



The examination of sections of coal under low powers, either as 

 transparent, or opaque objects, is almost useless ; but sections 

 averaging between the two and three-hundredths of an inch in 

 thickness, under a quarter, or an eighth objective, show a structure 

 as unmistakably as do sections of recent vegetable organisms. The 

 teachings resulting from examination of such sections have been truly 

 and clearly brought before the public by Professor Huxley in a lec- 

 ture at Bradford in January last, and again at Leicester in November 

 last, and reported in the " Contemporary Review." The means 

 of confirming these observations is in the hands of anyone accus- 

 tomed to prepare objects for the microscope, while the material is 

 close to our hands at any moment. The method of proceeding is 

 as follows : — 



A piece of coal being selected, a surface is at first obtained 

 roughly by a file, or piece of sandstone ; then a finer, by means of 

 a hone, or piece of fine glass paper ; then a still finer, by means of 

 pumicestone, and after rubbing upon Arkansas stone, finally brought 

 to the highest polish possible by friction upon plate glass. 



If the coal be very friable (which it sometimes is), it will be 

 necessary to macerate the specimen in thin shell lac varnish and 

 dried, before the whole process can be accomplished. 



In order to secure success, it is impossible to bestow too much 

 pains in this preliminary operation. 



Having made a good surface, next cement it to a glass slip by 



l 2 



