38 ELEMENTS OF LABORATORY WORK 



31. Relation of Temperature-changes to duality and 

 Quantity of Matter. 1. Observe that when two quantities of 

 water at different temperatures are mixed, the resultant tem- 

 perature of the mixture is intermediate and varies with the 

 quantity and temperature of each. 



2. Observe that when equal quantities of turpentine and 

 water at the same temperature are mixed respectively with 

 equal quantities of water at a different temperature, the 

 mixtures do not agree in temperature. 



3. Observe that if two quantities of water at the same 

 temperature, one of which is double the other, be mixed 

 respectively with two other quantities of water, also in the 

 ratio of 2 to 1, but at a different temperature, then the same 

 temperature results in each case. Observe also that this 

 holds true for other liquids, e.g. turpentine, and for other 

 relative quantities, e.g. 3 to 1, or 2 to 3, and so on. 



The above exercises show that, when bodies of different 

 temperatures are brought together, the resultant temperature 

 varies with the quantity and nature of the matter contained 

 by these bodies. The same temperature, however, is obtained 

 if two quantities of matter, one at a high and one at a low 

 temperature, be mixed, as is obtained when we mix two 

 different quantities, at the same respective temperatures, 

 either of the same or a different kind of matter, provided only 

 the same relation in quantity be maintained. It is almost 

 unnecessary to state that this experiment, and all others too, 

 will be accurate only when our observation includes everything 

 that is changed during the operation. Any change of tem- 

 perature in one body proceeds simultaneously with changes 

 of some kind in one or more other bodies. We are now con- 

 cerned, however, with co-existent thermal changes only, and 

 these may be observed to be reciprocal, i.e. a certain quantity 

 of matter rises in temperature while another quantity falls. 

 If a hot body be exposed in a room, the temperature of the sur- 

 rounding bodies, including that of the air and the walls of 

 the room, will rise, whilst its own temperature falls, until 

 there is the same temperature everywhere. Hence arises the 

 necessity in these preliminary observations of using liquids 



