210 Il'ioijraphii of BerzeUus. 



element unites with one atom of another, assumed also that 

 when, for example, several oxides of an element existed, the 

 oxygen atoms of the higher oxides were multiples of the oxy- 

 gen in the lowest oxide. But when only one oxide was 

 known, it was obviously very hazardous to assume that it 

 consisted of equal atoms of both elements, without taking 

 any notice of the other relations of this compound. Berze- 

 lius studied all the circumstances with the greatest attention ; 

 and the caution, as well as penetrating tact with which he 

 proceeded, are evident from the fact, that, when subse- 

 quently, Mitscherlich, by his important discovery of Isomor- 

 phism, furnished an admirable means of recognising with 

 certainty bodies having similar atomic composition, it was not 

 necessary for Berzelius to make any alteration in his views. 



Only upon one occasion did he feel himself compelled to 

 modify his views regarding the arrangement of atoms in 

 compound bodies. On the first establishment of his system, 

 he was of opinion that in the simple compounds, such as 

 oxides, there must be the most simple proportion, and that of 

 two atoms of the radical to three of oxygen appeared to him 

 to be too complex. Since in the oxides of iron the oxygen 

 was in the proportion of two to three, he assumed that per- 

 oxide of iron consisted of one atom of metal and three atoms 

 of oxygen, the protoxide and all those similar to it as con- 

 sisting of one atom metal and two atoms oxygen. It was 

 not until later in the year 1827, that Berzelius, particularly 

 influenced by the proportions of the elements in the oxides 

 of manganese, chromium, and sulphur, decided upon assum- 

 ing, that, in the strongly basic, or so-called electro-positive 

 oxides, there was but one atom of metal and one atom of 

 oxygen, and, consequently, that the atomic weights formerly 

 adopted by him must be reduced to one half. The higher 

 oxides, such as peroxide of iron, would then contain three 

 atoms of oxygen to two atoms of metal. 



At that time, Berzelius adopted the view, that when a 

 simple body is converted into the gaseous state, one volume 

 of the gas corresponds to an atom. For this reason, water 

 was alywas regarded by him as being composed of one atom 

 oxygen and two atoms hydrogen. He held this opinion 



