ON tHE SUPPOSED CURRENTS IN HOT LIQUIDS, $•$ 



the hot and cold particles of* the liquid, the caufes afligned by 

 Count Rumford for the exiftence of the fuppofed cnrrents, is 

 capable of producing only a motion fo very flow, as fcarcoly 

 to be vifible. But what is null more puzzling, if poffible, is 

 the total difcordance between thcfe rapid currents and the 

 flow rate at which the liquid cools. If the water actually 

 moved with the rapidity indicated by the amber, and it it 

 parted with the tenth part of the caloric neceflary to produce 

 that rapidity, the whole of the liquid would cool down to 

 the temperature of the atmolphere almoft in an inftant : 

 whereas, in fact, feveral hours are always neceflary to pro- 

 duce that effect. 



Thefe apparent anomalies fuggefted the poflibility of the Experiment u 

 motion of the amber being occafioned by fome other caufe ^ **^ Mwi/ith 

 than currents in the liquid, and made it neceflary to examine poured clear 

 the matter with more attention. The following experiments ^3™^ t " C 

 occurred to me as the fimpleft method of determining whether mix them. Se- 

 the fuppofed currents exifted or not. Into the glafs veflel A, ^^]^ m 

 PI. VIII. Fig. 2, I poured water, tinged blue with the juice of thefe fluids. 

 red cabbage, till it flood at the height ?n. Then by means of a 

 flip of cork fwimming on the furface of the blue infufion, and 

 a funnel terminating in a long capillary tube, I fucceeded (after 

 feveral unfuccefsful attempts) in filling the veflel with water to 

 the height n, without mixing it with the blue infufion. Thus I 

 had two liquids in the veflel A, both very nearly of the fame 

 fpecific gravity, the undermofl of a blue colour, the upper- 

 mofr. colourlels, and the plane m, which feparated them, 

 pretty well defined. There were feveral opaque bodies 

 floating through the blue infufion, which anfwered the pur- 

 pofe of the amber. 



My intention was to apply heat to the bottom of the veflel It was expected, 



A, which I knew would produce the fuppofed currents, that when heat lhooM 

 • r 1 t r . n r • t ,. • • ^t ., be applied, «r£ef 



is to lay, would let the floating bodies in motion. Now if that the lower 



thefe floating bodies were really put in motion by currents, it fluld , w . ou,d , 7 



is evident that part of the blue infufion muft accompany them. cur rer.t and carry 



But this would become evident whenever they paflcd the U P the opaque 



plane m, and entered into the colourlefs medium : for in that t - nefe £ jj es a 



cafe they would be accompanied by a blue current, which would afcend 



would be vifible to the eye. Whereas if the floating bodi«s t&ttiS^mk 



were in motion while the water continued at reft, they would confequently 



pafs the plane m, and move through the colourlefs ™^™fj?fjj* tmm 



G 2 Without carrel, 



