J14- Royal Society of Copenhagen. 



uEquatio qusefita ad minimum determinanda eft pro qua- 

 tuor diverfis cafibus. lino, Si lignum vel cefpes caminarias 

 feu carbones foffiles in fornace deuruntur, Ut fpatium aeris 

 inclufum, e. gr. cubiculi calefieri poffit. ido, Si in foco 

 fluido cuicunque coquendo infervient. 3//0, Si materise molli 

 indurandx, e. gr. in camino laterario lateribus coquendis. 

 4^, Si materiis duris liquefaciendis, e. gr. metallis five in 

 clibano five in uftrina fundendis infervient. 



Singula? sequationes experientia duce ita analyfis ope de- 

 tcgendse et inftituendje -funt, ut ex ipfis computari poffit 

 ratio effe£tus calorifici seque ac ufus ceconomici cujufcunque 

 fpeciei ligni, cefpiiis caminarii et carbonum fofiilium. 



" To di (cover the functions of all thofe quantities which 

 " conjointly determine the degree of the effecl: of heat pro- 

 " duced by every combuftible fubftance employed for econo- 

 u mical purpnfes, whether wood, turf, foffil, or pit-coal of 

 " whatever fpecies. 



'* The required equation mud be determined for four 

 M different cafes. J/?, When the wood, turf, or pit-coal la 

 " burnt in a ftove, that the inclofed quantity of air, for 

 " example of a chamber, may be fufRciently heated. idly t 

 " When they are employed as fuel for boiling any liquid. 

 " 3^/y, When they are employed for hardening any foft 

 *' fubftance, for example, in a brick-kiln for baking bricks. 

 " 4//j/y, When employed for melting hard fubftances, fuch, 

 " for example, as fufing meuls either in an effaying furnace 

 *' or a melting furnace. 



" Each of thefe equations muft be fo deduced from ex- 

 " periment, by the help of analyfis, that they may ferve for 

 •• computing the ratio of the effects of the heat and the 

 " economical advantages of each fpecies of wood, turf, and 

 " pit-coal." 



III. IN PHYSICS. 



Experiments invenire maximum caloris gradum quern 

 calefadli vapores aquei cum aliis corporibus communicare 

 poffunt ? An ea pars aqua: in olla Papiniana, quae non in 



vapores 



