176 Biography of Berzelius. 
iron, would then contain three atoms of oxygen to two atoms of 
At that time, Berzelius adopted the view, that when a simple 
hody is converted into the gaseous state, one volume of the gas 
corresponds to an atom. For this reason, water was always re- 
garded by him as composed of one atom of oxygen and two 
atoms of hydrogen. He held this opinion firmly, and disputed the 
hypotheses of Thomson, Dalton, and other chemists, who assumed 
that in two volumes of hydrogen there were as many atoms as in 
one volume of oxygen. Subsequently, when by the direct de- 
termination of the specific weights of sulphur, phosphorus, and 
mercury vapors, made Dumas and Mitscherlich, this assump* 
tion of Berzelius was not generally confirmed, he limited its appli- 
cation to the permanent gases alone. 
He was on this account compelled frequently to assume two — 
atoms where other chemists assumed only one atom. He there- 
fore introduced double atoms in those cases where they were the 
equivalent for one atom of another substance. Many chemists 
phorus, as double those adopted by Berzelius; many French 
tion of his Lehrbuch, he has assigned for doing this, are so strong, 
that they cannot well be set aside. These he derives especially 
