LETTER FROM JOHN PERCY, M. D., TO C. LYELL, ESQ. 205 



Incineration : 



14-27 grains gave of Ash, 1*66, or 11-63 per cent. 

 2-28 do. 0-27, or 11-84 do. 



Mean 



11-73 



In the first analysis, both of the Mauch Chunk and the Frostburgh Coal, 

 there is a very decided error in the determination of the carbon ; and the differ- 

 ence in the per centage of hydrogen in the analyses of the last-mentioned coal 

 is much greater than I should wish. In the following table, therefore, we will 

 take the mean of the second and third analyses only of the two varieties of coal 

 in estimating the per centage of carbon ; and the mean of the three of each 

 variety in estimating the per centage of hydrogen. We shall not then, I 

 am sure, commit any serious error : — 





POMEROV. 



Frostburgh. 



M. Chunk. 



Carbon 

 Hydrogen 

 Oxygen - 

 Nitrogen - 

 Ash 



76-70 

 5-67 



11-32 

 1-71 

 4-60 



78-80 

 4-59 

 2-51 

 2-37 



11-73 



84-98 

 2-45 

 1-15 

 1-22 



10-20 



Total - 



100-00 



100-00 



100 00 



4. Worcester Plumbaginous Anthracite. 



I selected for analysis those small fragments which appeared to be most free 

 from the associated rock. It had the touch and somewhat of the lustre of 

 plumbago ; it gave a streak on paper, and the mortar in which it was triturated 

 became coated and polished, as if from common plumbago. Dried at 120° 

 Centig. 



Analysis. 

 8-00 grs. gave of 



Water, 0-670 = Hydrogen, 0744, or 0-926 per 100. 



Carbonic Acid, 8 -316 = Carbon, 2-268, or 28-350 do. 



Nitrogen. 



I found I had not sufficient of the same specimen to make a nitrogen analysis. 

 I ascertained, however, that what remained of the other fragments contained 

 nitrogen. On heating in a test-tube with the soda-lime mixture, ammonia was 

 evolved, as proved by 



1. Red litmus-paper being turned blue ; 



2. By the appearance of dense white fumes on holding the stopper of the 



hydrochloric acid bottle near the mouth of the tube ; 



3. And, also, characteristically by the smell. 



Incineration. 

 6-745 grains gave of Ash, 4-625, or 68-569 per 100. 



