'Experiments refpe&ing Heal. a I 



No. %. -\ Here, in i \ minute, the thermo- 

 ° / 54t I meter rofe 38'- degrees by re- 



il. 93 \ fle&ed rays ; and, when the 



. I covered the mirror. [ mirror was covered up, it fell 

 3' 65 ) in the next 1 \ minute, 28 de- 



grees. On which account we cannot but allow that certain 

 rays, whether it be thofe that fhine or not, iffue from an 

 ignited poker, which, are fubje£t to the regular laws of re- 

 flection, and have a power of heating bodies. 



[To be continued.] 



IV. Account of fome hitereji'ing Experiments, performed at 

 the London Pbilofophical Society, refpecling the Effecls of 

 Heat, excited by a Stream of Oxygen Gas thrown upon 

 ignited Charcoal, on a number of Gems and other refrac- 

 tory Subjlances fulmitted to its Aclion; with a Defcription 

 of the Apparatus employed *. 



I 



T is well known that no methods with which we are yet 

 acquainted, are capable of exciting a degree of heat which is 

 at all to be compared with that produced by the agents «m- 

 ployed in the operations about to be defcribed. The finking 

 experiment of the deflagration of iron-wire in oxygen gas is 

 frequently accompanied with phaenomena, not hitherto at- 

 tended to as they deferve to be, which furnifh ftrong proofs 

 in fupport of this aflertion. 



A receiver, or bell-glafs, that will hold about two quarts, 

 with an aperture at the top of about one inch in diameter 

 (fuch as is now ufually denominated " a deflagrating glafs"), 

 is charged with oxygen gas, in the ufual manner, on the fhelf 

 of a pneumatic tub, the aperture being flopped with a cork, 

 or, which is better, coyered with a piece of (late, or other 

 fuitable fubftance, ground flat fo as to lie clofely on its edges. 

 If the veffel be then removed from the fhelf into an earthen 

 plate, with a fufncient quantity of water in it to cover the 

 edge of the receiver, and prevent the efcape of the gas from 



* from the unpublifhed minutes of the Society. Wc are promifed, 

 from the fame quarter, feveral other interefting communications. 



below, 



