140 Biographical Accoiinl o/Dii. Woll.\5TON, ly Dr. TnoM.NS Tuomsox. 



2. It is well tuown to every individual wbo takes any interest in che- 

 raieal investigations^ tbat wbat is called DaUon's atomic theory was made 

 known to the public about tbc year 1804. According to tbat tbeory 

 every simple substance is an atom baving a determinate weigbt. Bodies 

 combine eitber atom to atom, or an atom of one witb a certain number of 

 atoms of anotber. At tbat time cbemists were in possession of bardly 

 any accurate analysis of salts or of cbemical compounds in general. Mr. 

 Dalton founded bis tbeory on tbe analysis of two gases, namely, protoxide 

 and deutoxide of azote; tbe first consisting of a certain quantity of azote 

 united witb a determined weigbt of oxygen, tbe second of the same quan- 

 tity of azote united to twice as much oxygen. Tbe first of these he con- 

 sidered as a compound of one atom of azote with one atom of oxygen, and 

 the second of one atom of azote united witb two atoms of oxygen. 



In tbe year 1808 I supplied Mr. Dalton witb two instances of suuilar 

 combination, namely : — 



1. Oxalate of potash. 

 Binoxalate of potash. 



Oxalate of strontian. 

 Binoxalate of strontian. 



After tbe perusal of ray paper on oxalic acid, Dr. Woliaston read a paper 

 to the Royal Society on super-acid and sub-acid salts, which was published 

 in tbe Philosophical Transactions for 1808. In this paper he gives six 

 examples of similar combinations, namely : — 



1. Carbonate of potash. 

 Bicarbonate of potash. 



2. Carbonate of soda. 

 Bicarbonate of soda. 



3. Sulphate of potash. 



Bisulphate of potash. 

 4. Oxalate of potash. 

 Binoxalate of potash. 

 Quadroxalate of potash. 



3. About the beginning of tbe present century, Mr. Hatchett dis- 

 covered a new metal in a mineral from America, a specimen of which was 

 in tbe British Museum. To this new metal he gave the name of colum- 

 hium. Soon after Mr. Hatchett's discovery, a metallic substance was 

 detected in Sweden by Mr Ekeberg, differing from every other witb 

 which be was acquainted. This new metal be distinguished by the name 

 of tantalum. The discovery of Hatchett was made known to tbe public 

 in tbe Philosophical Transactions for 1802, and that of Ekeberg in tbe 

 memoirs of tbe Swedish Academy of Sciences for 1802. 



In tbe year 1809 Dr. Woliaston procured specimens of tbe Swedish 

 mineral containing tantalum, and of tbe mineral in the British Museum 

 containing columhium, extracted a little of the oxide of tantalum from 

 the one, and of the oxide of columbium from the other, and by a very 

 ingenious comparison of the two, demonstrated that both oxides are 

 identical, and that columbium and tantalum constitute one and tbe same 

 metal. These results were published by Woliaston in 1809 in tbe Philo- 

 sophical Transactions, and exhibit a very satisfactory display of his 



