ON THE HEAT EVOLVED 



All woods contain much moisture, even when apparently 

 very dry ; and, as the persons alluded to have neglected to 

 determine the quantities of absolutely dry wood, burned by 

 them, much uncertainty prevails in the results of all their 

 experiments. Another source of uncertainty, lies in the great 

 quantity of heat suffered to escape with the smoke and other 

 products of the combustion."* Again,! "attempts have been 

 long ago made, to measure the heat that is developed in the 

 combustion of inflammable substances ; but the results of the 

 experiments have been so contradictory, and the methods 

 employed so little calculated to inspire confidence, that the 

 undertaking is justly considered as very little advanced. I 

 had attempted it at three different times within these twenty 

 years, but without success. After having made a great num- 

 ber of experiments with the most scrupulous care, with appa- 

 ratus on which I had long reflected, and afterwards caused to 

 be executed by skilful workmen, I had found nothing, how- 

 ever, that appeared to me sufficiently decisive to deserve to be 

 made public. A large apparatus in copper, more than twelve 

 feet long, which I had made at Munich fifteen years ago, and 

 another scarcely less expensive, made at Paris four years ago, 

 which I have still in my laboratory, attest the desire I have 

 long entertained, of finding the means of elucidating a ques- 

 tion that has always appeared to me of great importance, both 

 with regard to the sciences and to the arts. At length, how- 

 ever, I have the satisfaction of announcing to the class, that, 

 after all my fruitless attempts, I have discovered a very simple 

 method of measuring the heat manifested in combustion, and, 

 1 his even with such precision, as leaves nothing to be desired." 



It will not be necessary to describe the Calorimeter used by 

 Count Romford, more particularly, than to say, that it consists 

 of a small copper receiver containing water. In the inside is 

 a flat worm, also made of copper, bent so as to pass horizon- 

 tally three times from one end of the receiver to the other. 

 This worm passes down through an aperture in the bottom. 



'Nicholson's Journal, XXXV. 105. 

 tlbi.l. XXXII. 105. 



