26i The late Dr. Thomas Thomson. 



ever, that was published after Dalton, in illustration of his theory,* Dr. 

 Thomson not only substituted alphabetical symbols for the circles of 

 Dalton, but he employed them in the construction of formula, for the 

 purpose of building up and picturing to himself the composition of oxalic 

 acid, as ascertained by the substances obtained during the application of 

 heat to oxalate of lime. 



"Let an atom of oxigen," he says, "be w, an atom of carbon c, and 

 an atom of hidrogen h. An atom of oxalic acid may be represented by 

 4 w + 3 c + 2 h." " Three particles of oxalic acid resolve themselves 

 into these substances in the following proportions : — 



" 4 particles of carbonic acid, =: 8 lo + 4 c. 



2 particles of carburetted hidrogen, = 2 c + 4 /t. 



2 particles of carbonic oxide, = 2 it; + 2 c. 



2 particles of water, = 2w + 2 /». 



1 particle of charcoal, ..... = 1 c 



Total, 1-2 m; + 9 c + 6 h. 



3 particles of oxalic acid, =12 w + ^ c+6 /j." 



" Sugar," he says, "is a compound of 12 atoms, namely: five of oxigen, 

 three of carbon, and four of hidrogen ; the weight of an integrant particle 

 of it is 47-5, and its symbol is 5 ly + 3 c + 4 A." Berzelius greatly 

 extended the use of these symbols, but he did not claim the merit of 

 having introduced them in chemical investigations. Dr. R. D. Thomson, 

 in the paper to which I have already referred, quotes a passage to this 

 effect from a work of Berzelius published in Swedish in 1814, where he 

 says that he strictly "followed the rules for this purpose given by 

 Thomson in his system of chemistry" (och skall dervid folga en enledning 

 som Thomson gifvit i sin kemiska handbok.) "The work," continues 

 Dr. E. D. Thomson, " in which this passage occurs, entitled ' Forsok att 

 genom anvandandet af den electrokemiska theorien &c., grundliigga for 

 mineralogier' af J. Jacob Berzelius, Stockholm, 1814, page 18, was sent 

 by Berzelius to Dr. Thomson in the same year, with a request, in a letter 

 which is still extant, that he would endeavour to procure a translator for 

 it. Dr. Thomson applied to Dr. Marcet and others without success, but 

 at last pi'evailed on his learned fi'iend, John Black, Esq., who so ably 

 conducted the Morning Chronicle newspaper for many years, to undertake 

 the task." 



It is not claiming, then, more for Dr. Thomson than his due, when we 

 say, notwithstanding the extensions and impi'ovements of Berzelius, that 

 ho was the inventor of the use of symbols as they are now employed in 

 chemical language. 



At a future time, if the Society think fit, I shall lay before it some 

 account of Dr. Thomson's biographical works. His Lives of the 

 Chemists must always be read with interest. 



• Philosophical Transactious for 1807, page 63. 



