THE CHEMICAL ELEMENTS — RAMSAY. 185 



lime, barytes, strontia, and magnesia. Some years later Scheele's 

 dephlogisticated marine acid, obtained by heating pyrolusite with 

 spirit of salt, was identified by Davy as in all likelihood elementary. 

 His words are: "All the conclusions which I have ventured to make 

 respecting the undecompounded nature of oxymuriatic gas are, I 

 conceive, entirely confirmed by these new facts. * * * It has 

 been judged most proper to suggest a name founded upon one of its 

 obvious and characteristic properties, its color, and to call it chlo- 

 rine." The subsequent discovery of iodine byCourtois in 1812 and 

 of bromine by Balard in 1826 led to the inevitable conclusion that 

 fluorine, if isolated, should resemble the other halogens in propreties, 

 and much later, in the able hands of Moissan, this was shown to be 

 true. 



The modern conception of the elements was much strengthened by 

 Dalton's revival of the Greek hypothesis of the atomic constitution 

 of matter and the assigning to each atom a definite weight. This 

 momentous step for the progress of chemistry was taken in 1803; the 

 first account of the theory was given to the public with Dalton's 

 consent in the third edition of Thomas Thomson's System of Chem- 

 istry in 1807; it was subsequently elaborated in the first volume of 

 Dalton's own System of Chemical Philosophy, published in 1808. 

 The notion that compounds consisted of aggregations of atoms of 

 elements united in definite or multiple proportions familiarized the 

 world with the conception of elements as the bricks of which the 

 universe is built. Yet the more daring spirits of that day were not 

 without hope that the elements themselves might prove decompos- 

 able. Dav} 7- , indeed, went so far as to write in 1811: "It is the duty 

 of the chemist to be bold in pursuit ; he must recollect how contrary 

 knowledge is to what appears to be experience. * * * To inquire 

 whether the elements be capable of being composed and decomposed 

 is a grand object of true philosophy." And Faraday, his great pupil 

 and successor, at a later date, 1815, was not behind Davy in his aspira- 

 tions when he wrote: "To decompose the metals, to re-form them, 

 and to realize the once absurd notion of transformation — these are 

 the problems now given to the chemist for solution." 



Indeed, the ancient idea of the unitary nature of matter was in 

 those days held to be highly probable. For attempts were soon 

 made to demonstrate that the atomic weights were themselves mul- 

 tiples of that of one of the elements. At first the suggestion was 

 that oxygen was the common basis; and later, when this supposition 

 turned out to be untenable, the claims of hydrogen were brought 

 forward by Prout. The hypothesis was revived in 1842 when Liebig 

 and Redtenbacher, and subsequently Dumas carried out a revision 

 of the atomic weights of some of the commoner elements and showed 

 that Berzelius was in error in attributing to carbon the atomic 



