124 Examination of the received DoSirinet 



will each have acquired, by the diffusion of the diflodged heat, 

 when it has come again to a itate of equilibrium ; a quantity 

 which muft in general be fo fmall as to elude all meafure- 

 ment in the petty procefTes of the laboratory. 



Are there any cafes in which heat is diflodged by the union 

 o c two liquids, and where, at the fame time, the volume of 

 the mixture is not reduced below that of the fum of the vo- 

 lumes of the ingredients? I do not recollect any. There 

 may, however, be fome, and it will be time enough to at- 

 tempt to explain them when they are adduced. In the mean 

 time, when a diminution of volume follows, or rather ac- 

 companies, the extrication of heat from any body, inftead of 

 running to the doctrine of latent heat being then made 

 fenfible (that is, heat being changed in its character), we 

 ought to content ourfelves with flaring an obvious fact, 

 namely, that the moleculae of the two liquids are fo con- 

 ftructed and formed as to admit of their coming clofer toge- 

 ther when mixed than they could when refpectively alone ; 

 and, of courfe, now fill reciprocally fpaces that, before their 

 mixture, were fdled with heat: the latter fubltance, in con- 

 fequence of being thus diflodged (for two fubftances cannot, 

 at one and the fame time, occupy the fame fpace), diffufes 

 itfelf among the furrounding bodies in proportion to their 

 capacities, conftituting in them, what it did in thofe it has 

 quitted, bulk or volume. 



What takes place in fuch cafes may be illuftratcd by one 

 of a different kind. If a pint of fmall fhot and a pint of dry 

 fand be mixed, they will occupy a lefs volume than two 

 pints; air is thrown out that was before lodged in the in- 

 terflices of both of them. Was it latent air then, and is it 

 fenjible air now ? Did it differ in its properties before and 

 after being ejected ? Weighing the ingredients before and 

 after mixture, will not tell how much air has been ejected : 

 but we know, notwithstanding, that its volume may be mea- 

 fured ; and fo may that of the heat driven out in the cafe 

 which this was brought to illuftrate. 



How are fluids in general meafured but by their bulk ? 

 or their weight, when circumftances will allow it? Water, 

 for inftance, in common cafes, is directly meafured by any 



veffel 



