&c. Sec. 



5$! OX" THE POWER OF FLUIDS TO CONDUCT HEAT. 



Dr. Blagden in the Philofophical Tran factions, from which it 



appears that water was cooled down to 21° or 22° without 



and the water freezing, I was curious to fee how far this law of expanfion 



may be cooled wou ] ( j continue below the freezing point, previoufly to the 

 down as low as ° r > r J 



5««or 6 9 with- congelation ot the water, and therefore ventured to put the 

 out freezing, water thermometer into a mixture of fnow and fait, about 

 25° below the freezing point, expecting the bulb to be burfl 

 when the fudden congelation took place. After taking it out 

 of a mixture of fnow and water, where it flood at 32° (that 

 is 53° per fcale) I immerfed it into the cold mixture, when 

 it role, at firft flowly, but increafing in velocity, it pafled 

 60°, 70°, and was going up towards 80°, when I look it out 

 to fee if there was any ice in the bulb, but it remained per- 

 fectly tranfparent: I immerfed it again, and raifed it 75 Q per 

 fcale, when in an inflant it darted up to 128°, and that mo- 

 ment taking it out, the bulb appeared white and opake, the 

 water within being frozen : fortunately it was not burft ; and 

 the liquid which was raifed thus to the top of the fcale was 

 not thrown out, though the tube was unfealed. Upon ap- 

 plying the hand, the ice was melted, and the liquid refumed 

 its flation. This experiment was repeated and varied, at the 

 expence of feveral thermometer bulbs, and it appeared that 

 water may be cooled down in fuch circum fiances, not only to 

 21°, but 5° or 6°, without freezing, and that the law of ex- 

 panfion abovementioned obtains in- every part of the fcale 

 from 4.2°| to 10° or below ; fo that the denfity of water at 

 10° is equal to the denfity at 75^. But as the difcovery of 

 this curious, and I believe hitherto unnoticed property, has 

 little to do with the object before us, I Ihall fay no more of it 

 at prcfent. 



(To be continued in our next.) 



SCIENTIFIC 



