PREPARING COAL FOR MICROSCOPIC EXAMINATION 



WEATHERED COAL 



















+ 65 MESH STORED 









< 











| SIZING 





CONTROL 

 SAMPLE 







/ 





| DECANT^ 





-65 MESH 











MINE. CORE DRILL 

 AND OUTCROP COAL 









\ / 



l 





Iio%kohK 



/ 





STAIN RESIDUE 

















1 





COAL 

 SAMPLE 





MACERATION IN 

 SCHULZE'S SOL. 



/ 







— | DECANT f 





DESTAIN 



DEHYDRATE 



IN ALCOHOLS 

















ROTARY DRILL 

 COAL SAMPLES 





SP. GR. 

 SEPARATION 







1 











DIAPHANE SOLVENT 

 AND 100% ALCOHOL 





CONTROL 

 SAMPLE 

















1 

















CONTROL STORED 1 



DIAPHANE SOLVENT 













CARBONACEOUS 

 SHALE 





MACERATION IN 



/ 





MIX WITH 



DIAPHANE 











HYDROFLUORIC ACID 



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Fig. 1. — Outline of the procedure used in isolating the small spores for microscopic study. 



ranks that range from brown coal to meta- 

 anthracite. The Pennsylvanian coal beds 

 in Illinois are high volatile bituminous coals 

 of C and B rank, and are composed of at 

 least two or more of the following ingre- 

 dients: vitrain, clarain, durain, and fusain 

 in variable proportions plus differing 

 amounts of mineral matter and moisture. 



Three methods of preparing coal for 

 microscopic investigation of the botanical 

 ingredients which are used in the United 

 States are: the chemical maceration meth- 

 od, the thin-section method, and the serial 

 microtome method. The thin-section meth- 

 od has been described by Thiessen, Sprunk, 

 and O'Donnell (1938). The serial micro- 

 tome method has been described by Jeffrey 

 (1910). The maceration method has been 

 described in part by various authors, but 

 since it is the method used in this investi- 

 gation it seems necessary to explain the 

 process in detail and to record additional 

 information which may be of help to 

 others. 



The maceration method was first de- 

 scribed by Franz Schulze in 1855, and with 

 modifications is widely used today not only 

 for the maceration of coal, but by botanists 

 for the maceration of modern plant tissues. 

 It consists of two phases, the partial oxida- 

 tion of coal and the dispersal of the humic 

 matter. The resistant plant spores, cuticle, 



etc. are freed, and may be isolated for 

 microscopic examination. 



The partial oxidation of coal may be 

 accomplished by a number of oxidizing 

 agents, the most common of which is termed 

 Schulze's solution. The solution is pre- 

 pared by mixing one part of a saturated 

 aqueous solution of KC10 3 with two or 

 three parts of cold concentrated HN0 3 , 

 which in the presence of an oxidizable 

 substance, in this case coal, reacts typically 

 as follows: 



2 HN0 3 + KCIO3 — > 2 N0 2 + KC1 + HoO + [4 O] 



The coal is then placed in a beaker and 

 covered with Schulze's solution. The oxi- 

 dation of coal follows: 



Coal + Oxygen (i.e. from Schulze's solution) — > 

 partially oxidized coal, i.e. oxides of carbon, 

 water, soluble acids, humic acids, etc. 



As shown in figure 1, weathered samples 

 of outcrop coal need no further oxidation, 

 and the first phase of the maceration process 

 is unnecessary. This is because the coal 

 has been oxidized by nature. 



Coaly or carbonaceous shales do not 

 macerate readily with Schulze's solution, 

 but maceration may be accomplished with 

 hydrofluoric acid. Hydrofluoric acid has 

 also proved helpful in the maceration of 

 certain tough cannel coals. 



The length of time necessary to prepare 



