COAL. 19 



and, as far as practicable, their extent and value. For tlie 

 evaporative power of coal, consult the papers of Dr. Fyfc, 

 in the Philosophical Magazine, and the extended observations 

 on American coals by Prof. W. R. Johnson, printed by order 

 of Congress. 



For full analyses of a large number (47) of coals, anthra- 

 cite, bituminous, and brown coals, as well of turfs and a few 

 woods, we refer to the An. Rep. of Liebig, Kopp, &c., p. 350, 

 1847-8. The same work, p. 353, gives the results of practical 

 experiments, together with analyses of many English coals (30), 

 conducted under the direction of De la Beche and Playfair. 

 They determined, 1. The practical evaporative power, the 

 number of pounds of water at 212° converted into steam by 

 IK) fuel. The average was 8.695ft) water evaporated, the 

 range being from 7 to 10. 2. The practical value after de- 

 ducting the coal left in the ash. 3. The evaporative power 

 calculated from the reduction of litharge by Berthier's pro- 

 cess. 4. Weight of the fuel per cubic foot of stowage, from 

 direct measurement. 5. Ditto, calculated from specific gra- 

 vity. 6. Percentage loss by attrition. 7. Evaporative power, 

 calculated from 2 and 4. We refer for these details to the 

 paper in the Mechan. Mag. 1849. 



Vaux's analyses of Engl. Coals, see in Journ. Fr. Inst. (3) 

 xvii. 197. 



Whoever witnesses the enormous amount of fine coal thrown 

 in heaps near the anthracite mines, regarded as valueless and 

 allowed to be washed away by streams, must have regretted 

 the waste of a quantity of fuel which will never be recovered. 

 Many patents have been issued in England with the view of 

 saving fine culm, by mixing it with adhesive combustibles, such 

 as coal, tar, &c., and pressing it into blocks. A late patent 

 proposes mixing dried and ground spent tan with rosin-oil, 

 or melted rosin, and compressing into blocks. (Lend. Journ. 

 Sept. 1850.) Another patent (L. J. Oct. 1850) uses, also, 

 refuse tan and peat with coal-tar, &c. But all these pro- 

 cesses would seem to be ineffectual at our anthracite mines, 

 because not sufficiently economical in comparison with the 



