SIMMEIIING OF WATER. 219 



iflued from the flame ilfelf, and formed drops on the ootfide. 

 As the included water became heated this condenfed water 

 evaporated, and left the furface again clear ; and at this pc* 

 riod the diffeminated air began to feparate and gave a dufty 

 appearance to the inner fiirface, which lafted about three mi- 

 nutes. At the end of this time the inner furface began to 

 clear; the peculiar noifeoffimmering Was heard; and bubbles 

 were feen fuddenly appearing and collapfing ; the retort itfelf 

 being agitated and the furface oF the water rifing and falling 

 by ftarts. The bubbles were pointed at top, fomevvhat re- 

 fembling fmall flames fuddenly appearing and vanifliing at 

 different parts of the furface. In the courfe of one minute 

 they grew larger and larger and collapfed at greater heights, 

 until at length they efcaped through the fluid without being 

 condenfed. This was the inftant of ebullition or boiling and 

 at this period the noife of fimmering ceafed and thai of boiling 

 was heard. 



Exp, 2, As this efTed appe^irs to arife decidedly from the Exp. 2. Water 

 upper water being colder than that near the boltom of ^he j^^^^^.^^^^^ ^^j.* 

 vefl'el, it was natural to infer that the appearances would befel. The effeda 



difl^erent according to its fi«:ure and magnitude. I therefore '^'f/''^^'^^'^^^^''^* 



° , . ^ ^ . , evident. 



took a boh-head, or fpherical glafs body, with a ftraight neck : 



Its diameter was four inches ; and when it was filled, a co- 

 lumn of water eight inches long flood in its upright neck. 

 The thicknefs of the glafs at its bottom was confiderable. At 

 33 minutes after three the lamp was lighted. At 40 minutes 

 bubbles of gas rofe fingly, and very little of the dufty appear- 

 ance was feen. At 58 minutes the noife of fiismering began, 

 and the collapling bubbles were plentiful and diftinft. Little 

 fireams or fountains of fleam rofe from particular points and 

 were condenfed ; and fome globes of half an inch diameter 

 afcended ck-ar of ihe bottom and collapfed in the fluid above. 

 At one minute afier four the bubbles reached the top of the 

 fluid without collapfing, and at this time the noife of flmmer- 

 ing ceafed. The lamp was then blown out. 



Exp. 4', A bright copper hemifphere, four inches in diame-Exp. 4. The 



ter, was filled with water at the temperature of 60 degrees. ^^P^'^^fP*^ 

 , r , . ■ 11 1- . , ■ repeated m- 



At tour hours three mmutes the lamp was lighted and water copper vefiTel 



became condenfed on the outfide. At five minutes the infide 

 furface had a dufty appearance, from bubbles of air immedi- 

 ately over the flame. The temperature was th^n 110^, and 



the 



was 

 a 



