^2i^ SIMMERING OF WATER, 



the outfide dry. At fix minutes bubbles of gas or air were 

 detached and rofe, the temperature being 12()^, and the va- 

 pour ot" fieani being vifiblc from the furface of the water. At 

 eight minutes the inlide furface was coated with large bubbles 

 or beads of airj temperature 150^. At nine minutes, temp. 

 165^, much vapour. At 94 min. temp, 175^, the bottom was 

 clear of bubbles, and the noife of limmering began. At 10 

 min. temp. 181'=', the fleam collapfmg bubbles were very evi- 

 dent, though, from their pointed Ihape, they were not imme- 

 diately obvious to an obferver looking ftraight down into the 

 ihining vellel. At 11 min. temp. ISO"^, noife very loud and 

 bubbles more and larger. At 12 min. temp. \Sb^, fome of 

 the bubbles broke at the furface, and the noife was lefs. At 

 12| min. temp. 204'',' the water boiled, and the limmering 

 noife was fucceeded by that of boiling. At 14- min. the lamp 

 was exlinguillied. 

 Exp. 5. Water Exp. 5. The water was fuffered to cool to 170°, and the 



already heated lamp was then lighted again, namely, at (our hours 18 mi- 

 does not fimmsr » & & » ^ 



fo much or fc» nutes. At 20 min. temperature 180®, the fimmeiing began ; 

 loiidly as water i^^j^ j^^j ^jlj ^j^\qj^ ^i,^ fjeam bubbles were feen very large: and 



qu'cklv rajied n i r i i i n i 



from a' low tern- lOOH afterwards, at 204.°, they rofe through the fluid, and 

 perac^re, j^g boiling took place by fountains or dreams of bubbles rifing 



from particular points. The firamering noife in this experi- 

 ment was much lefs than before. 



The thermometer was placed horizontally, with the greateft 

 part of its tube, and part of its bulb, out of the water. When 

 the bulb was plunged in the water, it fliewed 208**. 

 Conclufion. From thefc facts it appears to be clearly eftabliflied, that the 



caufe firft mentioned, namely, the condenfation of fleam 

 bubbles ia-their afcent through the cold fluid above, is the oc- 

 caiion of the noife of fimmering. In the fifth experiment the 

 ^ fuper incumbent water was hotter than that beneath, and con- 

 sequently the fimmering could not be produced but by fteam 

 at a higher temperature, and even then the collaplion of the 

 water was-lefs ludden and the noife lefs loud. 



Experiments 



