1825.] Mathematical Principles of Chemical Philosophy. 377 



Hence those bodies whose electrical relation is the most remote 

 from oxygen, or which tend most powerfully to the negative pole 

 of ithe* galvanic series, or which have the least tendency to the 

 eaithj^have also the smallest atomic capacities ; also the electri- 

 efel relation of oxygen is opposite to that of caloric, or, in other 

 words, the bodies which approach most nearly to oxygen in 

 ^rectrical relation, have the greatest attraction for caloric ; and, 

 'riierefore, the atomic capacities of oxides are greater than those 

 >6f the metals. iOiiofiixiiJ k:>imyik? lijiw amijj* yiJ 



ti ^M^hQ specific gravities be'febfMfjareti'A^^th'tht't'AMyjtK^'Mtee 

 J^Ker nearly is observed ; but since we do not know the relative 

 i%Srangements of the particles of different substances, we are 

 /febhged at present to consider them always similarly situated; 

 this may cause a difference of about one-third the specific 

 gravity. 

 ^i^j Analogy 4.— Those atoms which evolve most heat daring 

 their combination, are generally the hghtest. By inspecting 

 the table of forces, carbon, sulphur, and phosphorus, which 

 have the smallest forces, evolve more heat than zinc, tin, or 

 iron, whose force is greater; and these, more than copp6r, 

 silver, and gold* Lead forms an exception, and in fact the only 

 exception, in every case. Until more shall be known of the 

 laws by which combination is effected, we need not be surprised 

 if disagreements appeal-, for oxygen in combination does not 

 always possess the same specific gravity ; in the glass of an- 

 timony its specific gravity is 2*21 ; in phosphoric acid 5*1 ; in 

 oxide of arsenic 1*4 ; in red lead 3'2; oxide of manganese 3*1 

 or 2^7 ; red copper ore 1-47 ; iron mica 1*36. Therefore more 

 caloric remains in combination with the oxygen in some com- 

 pounds than in others. The results deduced from the best 

 data which are before the public, are not so coincident as 

 might be desired ; for not only are the capacities for heat and 

 the atomic weights variously ascertained, but, as I remarked in 

 a former communication, the specific gravities of porous bodies 

 are very incorrect, owing to the manner in which they are as- 

 certained ; and lest 1 should seem to arrogate the ability of 

 deciding those numbers on which the most eminent chemists 

 are not agreed, or of deducing conclusions from my own ex- 

 periments, calculated to favour the principles I advance, 1 have 

 /not argued from them in any instance, but have taken those of 

 Ithe most eminent modern chemists. The great apparent 

 ^density of oxygen in phosphoric acid appears to arise from a 

 s^eculiarity in the texture of phosphorus : its density may be 

 V considerably increased by compression ; and therefore the 

 boxygen must appear to have more density in the acid than it 

 oreally has ; its gravity was computed by the following for- 



inulae : specific gravity of oxygen in an oxide = ^' — ' ■•■■ • 



