174 



Domestic Science 



112. In the table of specific gravities given in 

 Chapter iv, that of ice is shown as 



0*917, i.e. ice is less dense than water, 

 a statement corroborated by the fa- 

 miliar fact that ice floats on water. 

 Hence, during the melting of a given 

 mass of ice, a contraction of volume 

 occurs. This phenomenon may* be 

 easily shown in the manner described 

 in the next experiment. 



EXPERIMENT 60. Break up some 

 ice into pieces small enough to be placed 

 in a flask of about 500 c.c. capacity. 

 Fill such a flask with the ice as com- 

 pletely as possible, and add enough 

 water, coloured with litmus and cooled 

 by dropping in a few pieces of the ice, 

 to entirely fill the spaces between the 

 lumps of ice and the neck of the flask. Fit the flask 

 with a well- fitting rubber stopper, carrying a long 

 piece of glass tubing and a paper scale as illustrated 

 in Fig. 53. In pushing the stopper home, some 

 of the water will be forced up the tube. Mark the 

 level to which it reaches on the scale. Allow the 

 apparatus to stand in a warm room. The consequent 

 melting of some of the ice will be accompanied by a 

 steady fall in the level of the liquid column in the 

 tube, showing that the volume of the resulting water 

 is less than that of the ice from which it is formed. 



113. During the increase of volume attendant upon 

 the change of water into ice, great force is exerted, 

 if the liquid be contained in a completely closed vessel. 

 The water-pipes within an ordinary house constitute 

 such a closed vessel when all taps are turned off. In 



Fig. 53. 



