20 REPORT— 1839. 



On a New Calorimeter, hy which the heat disengaged in combustion 

 may be exactly measured, with some introductory Remarks upon the 

 Nature of different Coals. By Andrew Ure, M.D, 



After some remarks on the quantity of sulphur in coal, and a table 

 of results obtained by analysis, Dr. Ure thus describes his Calorimeter 

 and its application. The apparatus which I employ consists of a large 

 copper bath capable of holding 100 gallons of water : it is traversed, 

 forwards and backwards, four times, in four different levels, by a zig- 

 zag horizontal flue, or flat pipe, nine inches broad, and one inch deep, 

 ending below in a round pipe, which passes through the bottom of the 

 copper bath, and receives there into it the top of a small black lead 

 furnace. The interior furnace, which contains the fuel, is surrounded, 

 at the distance of an inch, by another furnace, which case serves to 

 prevent the dissipation of heat into the atmosphere. A pipe, from a 

 pair of double-cylinder bellows, enters the ash-pit of the furnace at one 

 side, and supplies a steady current of air to keep up the combustion, 

 kindled at first by half an ounce of red-hot charcoal. So completely is 

 the heat which is disengaged by the burning fuel absorbed by the water 

 in the bath, that the air discharged at the top orifice has usually the 

 same temperature as the atmosphere. In the experiments made with 

 former water calorimeters, the combustion was maintained by the current 

 of a chimney, open at bottom, which carried off at top a quantity of 

 heat very difficult to estimate. My experiments have been directed 

 hitherto chiefly to a comparison of the heating powers of Welsh an- 

 thracite, Llangennech, and a few other coals. I have found, that the 

 anthracite, when burned in a peculiar way, with a certain small admix- 

 ture of other coals, evolves a quantity of heat at least 35 per cent, greater 

 than the Llangennech does, which latter is reckoned by many to be 

 the best fuel for the purposes of steam navigation. One half-pound of 

 anthracite, burned with my apparatus, heats 600 pounds of water 10° 

 Fahr., viz. from 62° to 72°, the temperature of the atmosphere being 

 66°; whereby no fallacy is occasioned either by the conducting 

 powers of the surrounding medium, or by a chimney current. We 

 thus see that one pound of anthracite will communicate, to at least 

 12,000 times its weight of water, an elevation of temperature of 1°, by 

 Fahrenheit's scale. For the sake of brevity, we may call this quantity, 

 or energy, 12,000 unities of heat. One pound of Llangennech, in the 

 same circumstances, will afford 9,000 unities : one pound of good char- 

 coal, after ordinary exposure to the air, affords 10,500: perfectly an- 

 hydrous charcoal would yield much more : one pound of Lambton's 

 Wall's-end coals affords 7,500 unities. It deserves to be remarked, that 

 a coal, which produces in its ignition much carburetted hydrogen and 

 water, does not afford so much heat as a coal equally rich in carbon, 

 but of a less hydrogenated nature, because, towards the production of 

 the carburetted hydrogen and water a great deal of latent or specific 

 heat is required : indeed, the evaporation of unburnt volatile matter 

 from ordinary flaming coals abstracts unprofitably a very large portion 



