328 M. Karsten*'s Observations and Experiments 



of carbon which it contains, or upon its proportion of hydrogen ; 

 but upon the relations which exist in the coal between the car- 

 bon, the hydrogen, and the oxygen considered together. A coal 

 very rich in carbon, in which the proportion of oxygen to hy- 

 drogen is as small as it can be, is very well adapted for the pur- 

 pose of lighting : it affords gas of excellent quality, although 

 not in great quantity. Although the quantity of carbon dimi- 

 nishes, and that of hydrogen increases, it does not follow that the 

 coal is better adapted for lighting, unless, along with the dimi- 

 nution of carbon, there is an increase of the relation of the hy- 

 drogen to the oxygen. 



M. Karsten, in this manner, makes application of his princi- 

 ples to the combustibles of which the analysis has been presented 

 in the preceding Table. 



Of the coals of Wellesweiler, near Saarbruck, No. VI., of the 

 country of Essen, in Westphalia, No. VII., and of Newcastle in 

 England, No. XI., the first and third of which present a some- 

 what larger proportion of hydrogen than the second, it is the 

 Essen coal, No. VII. that answers best for hghting, while the 

 Wellesweiler coal. No. VI., that which contains most hydrogen 

 of the three, is the coal which is least adapted for the same 

 purpose. The Beuthen coal, No. V., is still less adapted for 

 the purpose, and that from Berzenskowitz in Silesia, No. IV., 

 as well as the two kinds of coal indicated by Nos. VIII. and IX. 

 of the Table, are very bad for lighting. 



On the other hand, the Cannel coal. No. X., is superior to all 

 the others, not on account of its absolute contents in hydrogen, 

 which are not even so great as those of wood, but because the 

 hydrogen, at the same time, bears a great proportion to the oxy- 

 gen. It is this proportion, therefore, and not the absolute quan- 

 tity of the carbon, considered by itself, any more than the quan- 

 tity of hydrogen or of oxygen, that in a coal determines its rela- 

 tive capability of furnishing gas for lighting. The cannel coal, 

 No. X. contains 19 per cent, of oxygen, and the Wellesweiler 

 coal. No. VI., contains less than 15; yet the former is perhaps 

 better adapted than the latter for lighting by gas. 



There is a substance which is always met with in coal depo- 

 sits, and never in those of lignite. We have already made men- 



