OF THE USE OF STEAM 



AS A 



VEHICLE FOR TRANSPORTING HEAT. 



MANY attempts have been made, at different 

 periods, to heat liquids by means of steam in- 

 troduced into them ; but most of these have failed ; 

 and, indeed, until it was known that fluids are non-con- 

 ductors of heat, and, consequently, that heat cannot 

 be made to descend in them (which is a recent discov- 

 ery), these attempts could hardly succeed; for, in 

 order to their being successful, it is absolutely necessary 

 that the tube which conveys the hot steam should open 

 into the lowest part of the vessel which contains the 

 liquid to be heated, or nearly on a level with its bottom ; 

 but as long as the erroneous opinion obtained, that heat 

 could pass in fluids in all directions, there did not appear 

 to be any reason for placing the opening of the steam- 

 tube at the bottom of the vessel, while many were at hand 

 which pointed out other places as being more convenient 

 for it. 



But to succeed in heating liquids by steam, it is ne- 

 cessary, not only that the steam should enter the liquid 

 at the bottom of the vessel which contains it, but also 

 that it should enter it coming from above. 



The steam-tube should be in a vertical position, and 

 the steam should descend through it previous to its 

 entering the vessel, and mixing with the liquid which it 



