38 LEADING AMERICAN MEN OF SCIENCE 



"and I never burnt my mouth with them, or saw others meet with 

 the same misfortune, without endeavoring, but in vain, to find 

 out some way of accounting in a satisfactory manner for this 

 surprising phenomenon." 



Having in later life burnt his mouth, this time on a spoonful of 

 thick rice soup with which he was feeding himself while watching 

 an experiment, he determined to settle the question. Accordingly 

 he made some apple-sauce, and filling with it the jacket of his 

 double-walled thermometer, he found that it required twice as 

 many seconds to cool as when the jacket was filled with water. 

 Next he evaporated the apple-sauce, dried the fiber and found 

 that apple-sauce was 98 per cent water. So small an amount of 

 solid matter could not interfere with the transmission of heat 

 through the water, except by hindering the circulation of the water. 

 He deduces from this that the reason why animals and plants do 

 not more easily freeze during the winter is because sap and animal 

 fluids are thick and viscid, and also are prevented from circulating 

 freely by the cell walls. By heating a glass cylinder (test-tube) 

 containing a powder suspended in water, he was able to see the 

 warm currents ascending on one side and the cold currents de- 

 scending on the other, and to demonstrate that heat is not con- 

 ducted in liquids equally in all directions as it is in solids, but by 

 rising currents due to the expansion of the liquid by heat. He 

 found to his surprise that he was able to boil water in the upper 

 part of the tube while holding the lower part in his hand, and that 

 a cake of ice fastened at the bottom of the tube filled with boiling 

 water required hours to melt, while one at the top melted in a few 

 minutes. From these and many similar experiments he was led 

 to the conclusions that air, water and all fluids are non-conductors 

 of heat, and that heat cannot be propagated downwards in liq- 

 uids as long as they continue to be condensed by cold. 



He shows that life on this globe would be impossible if it were 

 not for the fact that water by cooling from about 40 F. to 32 F. 

 expands instead of contracts, for if ice were heavier than water it 

 would sink to the bottom, and all lakes would be frozen solid and 

 not melted during the summer. 



