208 Historical Review of Experiments. 



able to explain them without rejecting altogether that 

 hypothesis according to which it is supposed that the 

 heat which may be in the air is communicated directly 

 from one particle of this fluid to another. 



My researches on the propagation of heat in liquids 

 are sufficiently well known.* From them it has prob- 

 ably been seen how and in what manner I was com- 

 pelled by the results of my numerous experiments to 

 adopt the opinion with regard to this subject which I 

 have developed in my various writings. 



I have examined with the greatest care the objections 

 which have been offered to the deductions which I have 

 drawn from my experiments, and I can assert with 

 truth and to say this is a duty I owe to myself 

 that neither in these objections nor in the result of any 

 new experiment, as far as my knowledge extends, has 

 the least thing occurred which could serve as a reason 

 for altering my opinion in regard to this subject. In 

 a paper which I sent last year to the Royal Society 

 at London,f I think that I have proved that water is 

 really a non-conductor of heat, as I suspected six years 

 ago. 



I have now only a few words to say in addition, 

 about the various experiments which I made at different 

 times, to enable me (if it were in any way possible) to 

 answer decisively that important and much contested 

 question as to the materiality of heat, about which 

 philosophers have striven for so long a time. 



Those who regard heat as a substance must, of 

 necessity, assume that it possesses weight. If now the 



* A detailed description of my investigations in regard to this interesting subject is 

 contained in my seventh Essay, which appeared in London in the year 1797, in two 

 parts, together 188 octavo pages. See also Vol. I. p. 239. 



t See P- 274- 



