The Enquirer

Liquids are bad conductors of Heat (Caloric.)

Rumford has made some new experiments to prove that Liquids are bad conductors of Heat. It is his opinion that heat is propagated in, or rather conveyed and disseminated through Liquid bodies, principally if not altogether, by means of the streams which arise in the fluid, in consequence of those partial changes in the specific gravity of its strata, which indicate a change of temperature. This he has proved by the following experiment: He has a perpendicular tube about thirteen lines in diameter, which he keeps filled with boiling water: the bottom of the tube is plunged about 6-10ths of an inch into a tub full of water, in such a manner that its lower extremity is about half an inch distant from the bulb of a Thermometer immersed in the water at the bottom of the large tub. The Thermometer nevertheless remains Stationary. The experiment was several times repeated, and always produced the same result. From this the author concludes, that there is no direct communication of heat between the contiguous particles of water at different temperatures, which happen to touch each other. The mean apparent temperature, (he adds) that so readily establishes itself in a body of hot water, into which we have poured some cold water, must be produced by the currents (or streams) which arise from the difference of the specific gravities of the masses differently heated. I have for a long time suspected, that the suspension of solids that are dissolved in fluids, arises from no other cause than the imperfect fluidity of the menstrua. Since these bodies specifically heavier than water can nevertheless remain suspended in the liquid, it is impossible not to admit that the insulated particles of the cold water can equally remain immovable in the hot water with which they find themselves accidentally mixed.

Journal de Physique. Jan. 1807. P. 73.