[ 285 i 



XLVt. Researches upon the Heat developed in Comlustion^ 

 and in the Condensudon of f^apoiirs. Ktad before theFrench 

 Institute on t he ^Ath of February a?ul 30th of Noveinber 

 1812. Bij Count Rumford, F.R.S. Lieut. -General 

 in the Service of the King of Bavaria, Foreign Associate 

 of the IiHperiul Institute of France, (^c. &c* 



Attempts have been long made to measure the heat 

 which is developed in the coiiibubtion of inflammable 

 substances; but the results of the experiments have been 

 so contradictory, and the methods employed so little calcu- 

 lated to inspire confidence, that it is with reason that the 

 whole labour has been considered as not far advanced. 



I have undertaken it thrice within these twenty years, 

 without success. After having made a great number of 

 experiments with the most scrupulous care, and with an 

 apparatus long since contrived, and afterwards prepared by 

 clever workmen; I have nevrriheless done nothing worthy 

 of being made public. A large apparatus of copper, up- 

 wards of twelve feet long, which I constructed at Munich 

 fifteen years aco, and another one not less expensive, made 

 at Paris four years ago, and which I have still in my lat>o- 

 ratory, are testimonies of the desire which 1 have long en- 

 lertamed to find the ntcans of elucidating a question which 

 has always appeared to me of great importance both with 

 respect to the sciences and the arts. 



I have now the satisfaction to announce, that after all 

 my fruitless attempts, I have at length found out a very 

 simple method of measuring the heat which is manifested 

 in combustion, and even wiih a precii;icn which leaves 

 nothing more to be desired. 



In order that a proper eslimale may be formed of my 

 niethnd of operaiing, and of the confidence which may be 

 reposed in the restdis of my experiments, I have exhibited 

 njy apparatus to the class. 



The principal part of this apj^aratus is a kind of prismatic 

 receiver, 8 inches lun'rbv4| broad, and l^ inches in height, 

 constructed of very thin leaves of copper. This recii)ient, 

 wliich niav well merit the already celebrated name of Ca- 

 lorimeter, is furnished with a long neck or gullet near one 

 of its c\in.mitie^ three quarters of an inch in diameter 

 and three mrlico high, which is destined to receive, and to 

 keep in its place, a mercurial thermometer of a particular 



• Translated from a Frcnrli copy transmitted by ll.c atitlior to Sir Hum- 

 phry Davy, to whose kitiilfU'ss wc :ii« imii-bftJ for tlio coiumuiiicalioii.— 

 kciT. 



'form. 



