270 PROF. H. E. ROSCOE ON DALTON's 



Here follows the Table of the relative weights of the 

 atoms : — 



" Table of the relative weights of the ultimate particles of 

 gaseous and other bodies. 



Hydrogen i 



Azot 4*2 



Carbone 4'3 



Ammonia 5*2. 



Oxygen 5-5 



Water 6-5 



Phosphorus..... 7*2 



Phosphuretted hydrogen 8 2 



Nitrous gas 9*3 



Ether 9'6 



Gaseous oxide of carbon 9'8 



Nitrous oxide 137" 



Sulphur 14*4. 



Nitric acid 15*2 



Sulphuretted hydrogen 15*4 



Carbonic acid 15-3 



Alcohol 15^2 



Sulphureous acid 19*9 



Sulphuric acid 25*4 



Carburettcd hydrogen, froml - 



stagnant water t 



defiant gas 5*3 " 



In the second part of his 'New System of Chemical 

 Philosophy/ published in 1810, Dalton points out, under 

 the description of each substance, the experimental evidence 

 upon which its composition is based, and explains, in some 

 cases, how he arrived at the relative weights of the ultimate 

 particles in question. Between the years 1805 an( ^ J 8 10, 

 however, considerable changes had been made by Dalton 

 in the numbers, the Table found in the first part of the 

 new system being not only much more extended, but in 

 many cases the numbers differing altogether from those 

 given in the first Table published in 1805. It is therefore, 

 unfortunately, to a considerable extent now a matter of 

 conjecture how Dalton arrived at the first set of numbers ; 



