ATOMIC THEORY. 



hence Dr. Prout has fixed upon .i;902 as the fpecific gra- 

 vity of this gas. The fp. gr. of azote he affumes as .9722, 

 common air being 1 .000, for reafons ftated below. Now, 

 as ammonia is known to be compofed of one volume azote, 

 and three volumes hydrogen, condenfed into two volumes, 

 the fpecific gravity of hydrogen, according to thefe data, 

 muft be .0694. 



2. Atmofpheric air is admitted to be univerfally com- 

 pofed of about 21 per cent, of oxygen, and 79 per cent, of 

 azote, which fo nearly correfponds with one volume of 

 oxygen, and four volumes of azote, or 20 oxygen and 80 

 azote, that Dr. Prout has concluded that the above is its 

 true compofition, and confequently that it is a real che- 

 mical compound. ( See Air, Atmofpheric. ) Now the weight 

 of the atom of oxygen being fuppofed to be 10, and that of 

 the atom of azote 17.5, (Dr. Wollafton makes it 17.54,) 

 the fpecific gravity of oxygen gas, accordmg to thefe 

 data, will be i.iiii, and of azote .9722. But thefe num- 

 bers are multiples of .0694 for i.iiil -=r .0694 = 16, 

 and .9722 -r- .0694 =14- 



Such are two of the leading circumftances ftated in the 

 above eflay, which appear to have induced our author to 

 examine further into the fubjeft. For this purpofe, he 

 feems to have felefted a certain number of fubfl;ances, and 

 to have inftituted a feries of experiments on them, with the 

 view of afcertaining the truth of the opinions which he had 

 been led to adopt. Thefe experiments are faid to have 

 been numerous ; but their refults ai-e ftated in a very fum- 

 mary way, and in a manner certainly not very hkely to 

 carry convidlion. The whole is afterwards arranged in 

 tables, and there contrafted with the acknowledged refults of 

 other experimentalifts, with the view of fhewing how 

 nearly they coincide with each other. Thefe tables will 

 be found at the end of the prefent article, in an extended 

 form, and comprehending all the new determinations of Dr. 

 Thomfon. The near approach to whole numbers of the 

 weights of the atoms of all thefe fubftances, which have 

 been moft carefully examined, and are beft known, is cer- 

 tainly very fingular, and muft ftrike every one who has paid 

 attention to the fubjeft. At the fame time, no argument 

 can be advanced againft the opinion that certain relations 

 exift among the combining weights or atoms of bodies ; 

 on the contrary, this opinion feems much more probable 

 than that they have no connexion and are entirely inde- 

 pendent of one another. 



With refpeft to the queftion, whether the above opinion 



will ever be verified by aftual experiment ? it is difficult to 

 determine. The differences in general afTumed by Dr. 

 Prout are fo fmall, that in the prefent ftate of chemical 

 analyfis they may be fairly faid to be vi'ithin the hmits of 

 poflible error ; until, therefore, fome more refined methods 

 of experimental refearch be difcovered, we can fcarcely hope 

 the matter will be decided in this manner. 



We mentioned above, that there are a few fubftances 

 whofe fpecific gravity does not correfpond with the weight 

 of their atom ; thus the fpecific gravity of oxygen, for exam- 

 ple, is fixteen times that of hydrogen, while its combining 

 weight is only half or eight times that of hydrogen. 

 This at prefent cannot be explained ; but it is remarkable, 

 that the fpecific gravities are always fome multiple of the 

 weight of the atom. (See further on this fubjeft under 

 Theory, Atomic.) In the following tables will be found 

 other examples of the curious circumftance under con- 

 fideration. 



We {hall make no further obfervations at prefent, but 

 adopt Dr. Prout's plan of throwing together in tables the 

 great mafs of evidence on the fubjeft, and leaving the 

 queftion to be decided by the impartial judgment of our 

 readers. 



In the firft and fecond columns of the following tables 

 are given the fpecific gravities and weights of the atoms of 

 the different fubftances, fuppofing them to be in a gafeous 

 ftate, hydrogen being i ; " and if," fays Dr. Prout, " we 

 fuppofe the volume to be 47.2135 cubic inches, the 

 numbers will at the fame time reprefent the number of 

 grains this quantity of each gas will aftually weigh." 

 We may remark here, that if thefe views ftiould ever be 

 eftablifhed, they afford an excellent rational ftandard for 

 weights, as compared with meafures. Thus the cube of 

 the pendulum, for example, vibrating feconds, might be the 

 unit in volume of hydrogen, whole aftual weight might be 

 the unit in weight. Such a relation between weights and 

 meafures would be as general and immutable as the laws of 

 nature themfelves, and be worthy of the enlightened age in 

 which we live. In the third column are the correfted 

 numbers, the atom of oxygen being fuppofed, according to 

 Dr. Wollafton, Dr. Thi mfon, &c., 10 or i : and in the 

 fourth, the fame as obtained by experiment are ftated to 

 ftiew how nearly they coincide. .The other columns will be 

 fufficientlv underftood from infpeftion. The laft column in 

 the firft table contains the numbers recently afligned by- 

 Mr. Brande to the elementary fubftances. 



