/ROM WOOD AND COAL. 



wear one end of the receiver, to which it is soldered ; and thr 

 other extremity of the worm passes through the opposite end 

 of the receiver. A thermometer is introduced into the water 

 contained in the receiver; the woods, in thick shavings, and 

 other combustible bodies, are consumed in the mouth or bottom 

 of the worm, and the heat evolved in the combustion, is im- 

 parted to the water during its passage through the worm. 



The experiments consisted in elevating the temperature oJ 

 the water in the receiver 10°, commencing at 5° below, and 

 finishing at 5" above the temperature of the room; and the 

 comparison was made between the weights of di lie rent articles 

 required to be consumed to produce this effect, without regard 

 to time. 



The quantity of wood consumed, varied from 59 to 111 

 grains in each experiment. 



Upon these experiments it is necessary to remark, that the 

 passage of the mercury from 1 to 10° on the scale of the 

 thermometer, can scarcely be supposed to have been performed 

 in all the experiments tn equal periods nf time; and. Bince the 

 water would require unequal increments of heal in equal times, 

 to counterbalance its unequal decrements, and, possessing, as it 

 does, different capacities for heat at different temperatures, con- 

 sequently, a very slight inequality in point of time, in elevating 

 the mercury between the several degrees, would materially 

 atfect the results of experiments in which only a few mains of 

 the combustible were consumed. 



To these causes, and the absence of proper means to take 

 advantage of the heat produced in the combustion of the carbon 

 contain, d in the woods, maj I"- attributed the inacouracj "i 

 Count Rumford's results; a^ he states some of the woods to 

 evolve, by the combustion of equal weights, •> i per cent more 

 heat than others; whereas, the results of my experiments on 

 fori -sis vari< ties of wood, in equal weights, give the extremi - 

 of difference as only l 1 per cent. 



The result from charcoal is not given in the table, but the 



jrs, thai -The dry vegetable flesh of wood, produces rnon 



