262 Dr. Thomas Thomson s Observations 



Were the specific heat of azotic gas only 0-214 instead of 

 0*2698, we would obtain the mean number 0*375. 



Berzelius's atomic weight of azote is 0-88518. This mul- 

 tiplied by 0-2698, gives 0-2388, which is much farther below 

 0*375 than my number is above it. It is evident that Ber- 

 zelius's number is only one-half the true atom of azote. If 

 Mr. Dalton will consider the atom of azote with reference 

 to its specific heat, he will be satisfied that his ingenious 

 arguments in favour of 0*875, for the atom of azote, are not 

 so conclusive as he has hitherto thought them. 



Having sufficiently discussed the atomic weights in the 

 third compartment of the table, let us now attend to 

 the three substances in the first compartment, namely, 

 carbon, silicon and aluminum. Of these three, the specific 

 heat of carbon alone has been determined experimentally. 

 I have inferred the specific heats of silicon and aluminum 

 from those of silica and alumina determined by Neumann. 

 They may be seen at the beginning of the second table. 

 And the way in which I have deduced these specific heats 

 will appear when I come to consider the second table. 



It will be seen, on inspecting the table, that if we admit 

 0*75 to be the atomic weight of carbon, the product of that 

 number by its specific heat, instead of being 0*375 is only 

 0*19275, or about half that number. Shall we conclude 

 from this, that an atom of carbon is united with only half 

 the quantity of heat which is combined with the atoms of 

 the bodies constituting the third compartment of the table? 

 I think it more likely that we have occasioned the anomaly 

 by making the atom of carbon only half its real weight. 

 Let us suppose the atom of carbon to be 1*5 we have 1*5 x 

 0*257 = 0*385, a quantity which comes very near the mean 

 number 0*375. If the atom of carbon be 1*5, then 



Atoms. Atoms. 



Carbonic oxide is composed of 1 carbon + 2 oxygen 



Oxalic acid 2 ,, +3 „ 



Carbonic acid 1 ,, +4 „ 



Carburetted hydrogen of . 1 ,, +4 hydrogen 



Olefiant gas 1 ,, +2 ,, 



Alcohol of 1 atom oxygen + 1 ,, +3 ,, 



Ether of 1 „ + 2 „ +5 



