1879.] HEATING BY HOT WATER. 211 



the elevation of the flows above the boiler determines the rate of speed 

 at which the water moves, then it would be possible to attain elevation 

 sufficient to drive the water through the apparatus at a speed equalled 

 only by that of the electric spark. 



The rapidity of circulation of the water in the heating apparatus is 

 not measured or determined by the elevation of the flows above the 

 point on which the fire acts, but by the difference of the specific gravity 

 of the volumes of water in different points of the apparatus. The vol- 

 ume of least specific gravity will at all times occupy the highest, and 

 that of greatest specific gravity the lowest, point in the apparatus, unless 

 prevented from doing so through the defective adjustment of the latter, 

 which is not of unusual occurrence. Mr Inglis seems to think there is 

 some analogy between circulation as it takes place in the heating appa- 

 ratus and emptying a cistern by means of a syphon. A little considera- 

 tion will convince him that the two processes are not analogous. Cir- 

 culation does not empty the apparatus. The latter is an endless tube 

 full of water. At one point of this tube heat is applied, causing the 

 water to expand and become relatively lighter ; while at all other 

 points the water is contracting and becoming relatively heavier — hence 

 circulation. 



We will now look into C. M.'s paper. 



In reference to my statement that the particles of water are unable to trans- 

 mit heat to one another, C. M. asks, if this be so, " How does it come to pass 

 that water poured upon ice imparts its heat to it, the ice being then a solid ? " 

 In reference to this question, I may remark that hot ice would be a curiosity. 

 And the question implies, that by pouring hot water upon ice the latter be- 

 comes hot. I think, however, that it is impossible to heat ice either by pour- 

 ing hot water on it or by any other means. When in contact with a hotter 

 medium ice does not expand, and C. M. says "all bodies expand by heat." 

 Ice, however, is an exception to this rule, as, under the influence of heat, the 

 expanded particles of water of which ice is formed contract until reaching a 

 certain point, when they resume their liquid condition and are no longer ice, 

 the contracting and melting being confined to the external particles, those in 

 the interior not being affected by the thawing of those on the exterior of the 

 mass. To test the correctness of this, drop a ball of ice into a vessel contain- 

 ing hot water, let it remain for three or four minutes, then take out what 

 remains unthawed of the ball and drop it into a vessel containing cold water, 

 and the remaining portion of the ball of ice just taken from the hot water will 

 not raise the temperature of the cold, but will have an opposite effect, — thus 

 proving that solid particles of water are unable to transmit heat to each other 

 by conduction. And C. M. says solids transmit heat " by conduction only." 

 Now as the particles of water in a solid state, in the form of ice, are unable 

 to heat one another by conduction, the most reasonable inference is that they 

 are unable to do so in their liquid state. The next matter claiming attention 

 is where C. M. says, "the fact is, water transmits heat to water in the same 

 degree as it does to any other body." Well, "facts are chiels that winna 

 ding." Assertions, however, are not always facts, and we will consider the 

 above as only an assertion, and take it to mean that water parts with beat 

 to all bodies in the same degree. It is true water parts with heat to all other 



