ON THE ASSAYING OF COALS BY THE BLOWPIPE. 209 



deficiency ; and, thinking the subject of sufficient interest to be brought 

 before the Canadian Institute, I have embodied in the present paper, 

 the results of my investigations. The subject may be conveniently 

 considered under the following heads : — (1). Coal in its different as- 

 pects ; (2). Instruments and appliances ; (3). Operations. 



§ 1. DIFFERENT VARIETIES OF COAL. 



Without attending to minor distinctions or points of merely local 

 value, we may arrange all varieties of coal, so far as regards practical 

 purposes, under the following subdivisions : 



1. Anthracites. 



2. Anthracitic or Dry Coals. 



3. Caking or Fat Coals. 



4. Cannel or Gas Coals. 



5. Brown Coals or Lignites. 



These varieties pass by almost insensible transitions into one another. 

 Thus, the cannel coals are related to the lignites by the different kinds 

 of jet, some of which are referable to the one, and some to the other 

 subdivision. Between the caking and the cannel coals there are also 

 various links ; whilst the anthracitic or dry coals, on the other hand — 

 passing by excess of bitumen into the caking coals, and by a diminu- 

 tion of bituminous matter into the anthracites — serve to connect the 

 first and third divisions. The typical or normal specimens of each of 

 these five varieties, however, are sufficiently well marked. 



1. Anthracites. — The true or normal anthracites possess a brilliant 

 sub-metallic lustre, a degree of hardness varying from 3.0 to 3.25*, and 

 a specific gravity of at least 1.33. A specimen from Pensylvania 

 gave 1.51 ; another specimen, 1.44 ; one from the department of the 

 Isere in France, 1.56 ; and three from "Wales yielded respectively 1.33, 

 1.37, 1.34. It should be stated, however, that many of the Welsh 

 specimens belong strictly to the division of anthracitic coals, rather 

 than to that of the true anthracites. The normal anthracites exhibit 

 also a black or grayish-black streak ; and all are good conductors of 

 electi^city. The latter character may be conveniently shewn by the 

 method first pointed out by VonKobell. A fragment placed in a solu- 

 tion of sulphate of copper (blue vitriol) in contact with a strip of 

 zinc, will become quickly coated with a deposit of metallic copper : a 

 phenomenon not exhibited in the case of common coal. Deducting 

 ash and moisture, true anthracites present, as a mean, the following 



* Hausmann iu his Handbuch der Mineralogie, gives 2.5 as the extreme hardness of all 

 coals ; but this is evidently erroneous, as many specimens, not only of anthracite, but of 

 common and cannel coals, scratch calcareous spar. 



