598 



HISTORY OF SCIENCE. 



from time to time after the publication of his great work. He received 

 a pension at first of ^150 per annum, which was afterwards doubled. 

 Dalton died on the 2yth of July, 1844, and Manchester honoured her 

 great citizen by a public funeral, in which the procession was nearly 

 a mile in length. 



In one of his earliest papers (1802) on chemical subjects, Dalton 

 mentions a case of combination in multiple proportion : " The ele- 

 ments of oxygen may combine with a certain portion of nitrous gas, or 

 with twice that portion, but with no intermediate quantity." A little 

 later he found that the constituents of defiant gas and of carburetted 

 hydrogen gas were in each case nothing but carbon and hydrogen, and 

 also that for the same weight of carbon, carburetted hydrogen contains 

 exactly twice as much hydrogen as olefiant gas. In the " New System 

 of Chemical Philosophy " he takes the figures of Cavendish and Davy, 

 by which the per-centage compositions of three different compounds 

 of nitrogen and oxygen are expressed, and he shows that they agree 

 with the doctrine of multiple proportions. 



The Atomic Theory has so greatly influenced the progress of chemistry 

 that it is desirable the reader should realize the nature of the data upon 

 which it is founded. Perhaps no better illustration of the law of mul- 

 tiple proportions, and of the atomic explanation of that fact, can be 

 given than the instance of the compounds of nitrogen and oxygen 

 which Dalton himself gives. We shall give this in a tabular form some- 

 what similar to that set forth in Dal ton's work ; only, instead of using 

 the figures he quotes, which are results of but imperfect analysis, we 

 shall adopt those which the more exact and refined methods now in 

 use place at the disposal of the chemist. Five different compounds 

 of nitrogen and oxygen are known. 



