41 6 On the Heat developed in Combustion 



that such a fire dies of cold, an expression which with as 

 much force as justice describes the event as it really 

 happens. 



But if it be the cold communicated by the surround- 

 ing bodies which hinders a very small charcoal fire from 

 burning, could we not make it burn by guarding it in a 

 proper manner against the cold ? 



This is an experiment which I tried six years ago with 

 the greatest success, and which ended in my causing to 

 be made small portable cooking-stoves now in general 

 use in Paris, and elsewhere for aught I know. 



By surrounding the body of the stove with two strata 

 of enclosed air, the cooling of the fireplace and the char- 

 coal it contains is hindered ; and in this way the char- 

 coal burns perfectly well, and the fire is so well kept up 

 that it obeys a small register, which regulates the quan- 

 tity of air admitted into the body of the stove. 



Some judgment may be formed of the advantages 

 which ought to result from the use of these small porta- 

 ble furnaces in cooking, etc., arising from the saving of 

 time and combustibles, when we are informed that the 

 combustion may be regulated without any difficulty, so 

 as to consume the charge of charcoal in 20 minutes with 

 a brisk heat, or so as to keep up a moderate fire for 

 three hours. 



With these portable cooking-stoves it is indispensably 

 necessary to use kettles or saucepans of a particular 

 construction. They ought to be suspended by their 

 rims, in large circles of wrought-iron or copper, the bet- 

 ter to keep in the heat. The circle of a saucepan ought 

 to be half an inch more in breadth than the saucepan is 

 in depth. 



But to return to the main branch cf my subject. If 



