\36 ON FLUIDS. 



cake of ice in the bottom of a jar; he found that near the 

 furface of the ice the temperature was 40°, at the diftance of 

 three inches it was 159°, but at the diilance of feven inches 

 it was only 160°. Had the cold water acquired its elevation 

 of temperature by the currents produced, or by the fides of 

 the veflel, we ought, I apprehend, to have found the tem- 

 perature fpreading more uniformly : but though the firft four 

 inches only differ by one degree, we find the next three dif- 

 fering by 119 degrees. 

 5- Heat apP lie(1 5th. If liquids were abfolute non-conduclors of caloric, it 

 wards. would neceflarily follow, that when caloric was applied to the 



upper furface of different liquids, other circumftances re- 

 maining unchanged, and provided the liquid did not increafe 

 in fpeeific gravity by cooling, equal increments of temperature 

 would take place in equal times. 

 Apparatus for From feveral experiments it is probable, that fome liquids 

 "anfn^tring conduct caloric more rapidly than others. The following 

 heat downwards were undertaken with a view to afcertain more accurately 

 through Huids. this point . How faf t have f uccee( ] ed i j eave >ou to judge : 



A cylindrical veflel was turned out of wood, having its 

 tides 0.5 inch thick ; its height four inches, and its diameter 

 two. It has a moveable wooden top or cover perforated with 

 a hole in its centre a little more than an inch in diameter, into 

 which an iron cylinder of one inch in diameter could be eafily 

 introduced. This cylinder is fupported by a flight flanch or 

 (houlder-piece, and can be taken up by means of a firing at- 

 tached to its top. When the iron bar is in its place, its flat 

 lower extremity is 0.5 inch diflant from the bulb of a delicate 

 mercurial thermometer D E, which is fixed by wax, in a hole 

 perforating the cylinder near its bottom. This thermometer, 

 which was made by the late Ramfden, has a tube as fine as a 

 human hair, and is bended to a right angle, fo that its bulb 

 and part of its flem lie in the axis of the wooden cylinder. 

 This fliape was preferred, becaufe the ftem could be little 

 affected by the caloric tranfmitted by the fides of the veflel, 

 till after the bulb was acted on by the caloric of the iron bar, 

 A variety of experiments were performed with this apparatus 

 Into various 11 - in the following manner: The temperature of the room being 

 , w ids in fuccef- ft ea(li i y 67 o p. during the trials, a kettle of water was kept 



fion at 67* F. ,...-' . . & T , o , 



a cylinder of boiling over the fire : Its temperature was between 21 l u and 

 metal at *ia° 212°, and into this the cylinder of iron was futfered to re- 

 main. 



