9*^ 



tiu'oumlccl 

 by alinos- 

 Si)hercs of it. 



OxigS'n ".nd 

 hidrcgen 

 heated red hot 

 In contact 

 without 

 vnitin;. 



Th'it theory 

 explains all 

 tlie pheno- 

 mena of 

 caloric. 



No twa parti- 

 cles of matter 

 can touch rach 

 ether. 



ON TtlE EFFECTS OF ttEAt. 



cate, or hif^^her nitio. If the particles of the gasses were 

 merely dissolved in caloric, there seems to be no rea- 

 son, whj' they should ndt unite, accord in'^ to their affinity 

 for each other : for in a medium of uniform density, they 

 would be itnpelled by equal, ai7d contrary powers of the 

 medium ; there would therefore be no impediment to their 

 motion, and consequently to their union. This being 

 <»Tanted, the question still recurs : How does the addition 

 of caloric facilitate their union .'' The answer now is ob- 

 vious. By equalizinoj the density of the medium. Tt must 

 be observed, that, if a mixture of oxigen and hidrogen be 

 gradually heated, even to redness, in vessels which admit of 

 their expansion ; no union will take place*: for in this case, 

 the atmospheres will preserye their relative density. But 

 when the accumulation of caloric is sudden, as by an elec- 

 tric spark, the particles will not have sufficient time, to ar- 

 range it around themselves : by these means, the density of 

 the medium, will be rendered uniform: the particles 

 therefore, within the range of the spark, will unite; 'and, by 

 their union, give out a quantity of caloric, sufficient to 

 equalize the neighbouring atmospheres; and thus the whole 

 of the gasses, if mixed in due proportion, will combine. 

 Hence it appears, that the degree of ignition, which is 

 necessary for the combustion of oxigen and hidrogen, varies , 

 directly as the density of the atmospheres ; and inversely as 

 the affinity of the particles for each other. 



This is the explanation given by Dr. Higgins ; and to me 

 it appears much more satisfactory and intelligible than the 

 common one. But the theory, 1 conceive, may be extended 

 much farther; and will even be found to be sufficient to 

 account for all the phenomena, attendant on caloric. 



Let us suppose, that the particles of caloric are attracted 

 by those of all other bodies with a force, which varies in- 

 versely as the distance from the centre of these particles : 

 an<l also, that they are more strongly attracted by all other 

 bodies, than the particles of these last are by each other ; 

 or, in other words, that the particles of all bodies, have a 

 greater affiiiity for caloric, than for each other. This being 



• This experiment requires repetition. I do not recollect to hare 

 let wijh it «lsewliere. 



graated. 



