Biography of Berzelius. 103 
Art. X.—Biography of Berzelius ; by Prof. H. Ross, of Berlin. 
(Concluded from vol. xvi, p. 313.) 
Tue next subject to which Berzelius turned his attention be- 
longs to organic chemistry. It was a comparative investigation 
of tartaric and racemic acids. He first corrected his former anal- 
ysis of tartaric acid, in which he had given an atom more of hy- 
drogen than Prout and Hermann, and adopted the results of these 
chemists. But he then found that the crystallized tartaric acid 
had precisely the same on gone, as the effloresced racemic acid, 
and that both acids e same capacity of saturation —facts 
which, especially at ee ae were in the highest degree remark- 
able. This was one of the first clearly demonstrated examples 
that bodies of different characters may have the same composi- 
tion. Berzelius had, sometime before, observed a somewhat sim- 
a 
tion of phosphoric acid, which he called pyrophosphoric acid. 
On this occasion Berzelins combined together, in an interesting 
manner, what was known of these bodies, to which he gave the 
name Isomeric. This term has been universally adopted, now 
that the number of such bodies has been so greatly increased. 
From this time Berzelius frequently occupied himself with sub- 
jects which are certainly of the greatest interest to every thinking 
chemist, and indeed for every scientific man, since they are cal- 
culated to unfold to us somewhat more fully the nature of matter. 
He made known his views on this subject repeatedly, both in his 
« Jahresberichte, ” and in the several editions of his “ Lehrbuch.” 
inally, he assumed two essentially distinct kinds of isomerism, 
and, in the strictest sense of the word, called those bodies only 
grouped in different ways, forming compound bodies. ‘These iso- 
netic bodies may again be of two different kinds. a hey con- 
Stituents is the same, but in which the atomic ae Pe are not 
equal, but twice, thrice, etc., as great as that of each other. Such 
bodies Berzelius termed, for the sake of antithesis, Polymeric 
compoun nds. 
The other kind of isomerism Berzelius called Allotropism. It 
refers solely to elementary bodies, which, owing to causes not yet 
sufficiently understood, assume a different character from that 
which is usual to them, and, as it appears, re e 
mia 
