136 



ELEMENTARY GENERAL SCIENCE 



CHAP. 



both ends. Fill the flasks with water, alcohol, and oil of 

 turpentine respectively. Push in the corks till the liquid 

 stands in each tube at the same height. Put all three flasks 

 to the same depth into a vessel of warm water. Notice that 

 the expansion of the glass causes a momentary sinking of the 

 liquids ; that ultimately the expansions are very different. 



EXPT. 131. Fit a 2 oz. flask with a tight cork through which 

 a tube passes, the upper end of which is bent down and then 

 up at the end. Clamp the flask so that the end of the tube 

 dips under water in a basin. Fill a test-tube with water, and 

 invert it over the end of the tube. Warm the air in the flask, 

 and collect the expelled air in the 

 test-tube. 



EXPT. 132. Tightly fit a cork, 

 through which a straight tube 

 passes, into the neck of a 2 oz. 

 flask. Turn over and pass the tube 

 through the cork in the neck of a 

 wide-mouthed bottle, containing 

 coloured water. Warm the flask 

 with the hand or a flame so as to 

 expel some of the air, and let the 

 liquid rise in the stem, Fig. 55. 

 This constitutes an Air Ther- 

 mometer. 



EXPT. 133. Fasten two bulbs or flasks together (air-tight) 

 by a tube bent six times at right angles, and containing some 

 coloured liquid in the middle bend, Fig. 56. Show that the 

 liquid moves if one flask is warmed more than the other. 



FIG. 56. To illustrate Experi 

 ment 133. 



CHANGE OF TEMPERATURE. 



Its Measurement. The change of size which bodies ex- 

 perience when heated can evidently be made to provide us with 

 a method of measuring the change of temperature which they 

 undergo. If we can find some form of matter which expands 

 regularly as- it is heated, the increase in volume which results 

 can be taken as a measure of the change of temperature. Thus, 

 using the arrangement in Expt. 126, if we notice that the coloured 

 water in the tube rises through a certain number of inches after 

 being heated for some time, we can look upon this rise of the 

 level of the water in the tube as an equivalent of a certain 



