Heat as a Quantity 175 



very cold weather the water in the pipes may be frozen, 

 when the strain upon the material of the pipes is 

 usually sufficient to burst them, some of the water 

 escaping from the rent in the pipe and immediately 

 freezing, thus sealing up the pipe. As the weather 

 becomes warmer, this ice-seal melts, and the water 

 flowing through the pipe escapes at the point of bursting 

 commonly to be found in that portion of the pipes 

 situated near the top of the building causing much 

 annoyance and loss to the unfortunate householder. 

 It should be noticed that the burst occurs during 

 frosty weather, but that the awkward consequences 

 are not felt till a thaw sets in. This has given rise 

 to a more or less prevalent and entirely mistaken 

 impression that it is the thawing of the water which 

 causes the bursting of the pipes. 



114. The augmentation of volume taking place 

 when water becomes ice is but small when compared 

 with that produced when it assumes the gaseous 

 condition. 1 c.c. of water, boiling under atmospheric 

 pressure, gives rise to over 1600 c.c. of steam at the 

 same pressure. It is not easy to devise a simple 

 experiment in illustration of this, since the prevention 

 of condensation of the steam presents difficulty. From 

 another point of view most of us are familiar with this 

 phenomenon, for all work done by steam-engines 

 depends upon the great pressure exerted by the steam 

 escaping from boiling water, this pressure being due 

 to the effort of the steam to expand. Should this 

 pressure become too great for the material of the 

 boiler of the engine to support, the boiler bursts, unless, 

 by the use of suitable safety-valves some portion of 

 the steam is allowed to escape, and the pressure thereby 

 reduced. 



