346 Prof. Draper on the Allotropism of Chlorine 
In examining the action of the magnetic needle on the oxidi- 
zed crust of the Alabama iron, I found that most of this erust 
was attracted by the magnet, and that some of it exhibited con- 
stantly a powerful polarity, and attracted iron filings. On this 
occasion I examined the magnetism of some large pieces of me- 
teoric iron which had a polished surface. I found when these 
surfaces were placed vertically, that invariably the north pole of 
the needle was attracted by the upper edge, and the south pole 
by the lower one; and moving the needle from the upper toward 
the lower edge, along the surface, without being in contact with 
it, I arrived at a place where neither of the poles was attracted ; 
continuing on till I arrived near the lower margin, the south pole 
was again attracted. ‘This is invariably the case in whatever 
position in regard to the horizon the polished surface is placed, 
and however suddenly this position is changed. I found this to 
be the case with all iron. Whether this fact is known to those 
who have made magnetism an object of peculiar investigation, 
Icannot say. It is very possible that it must be attributed to 
the general magnetism of the globe. 
Art. [X.—On the Allotropism of Chlorine as connected with 
the Theory of Substitutions; by Joun Witiram Draper, 
M. D., Professor of Chemistry in the University of New York.* 
Tue researches of M. Dumas on chemical types have shown 
that between chlorine and hydrogen remarkable relations exist, 
indicating that the electrical characters of elementary atoms are 
not essential but rather incidental properties. The extension of 
these researches has given much weight to the opinion that the 
electro-chemical theory may be regarded as failing to account for 
the replacement of such bodies as hydrogen by chlorine, bromine, 
oxygen, &c. Ido not know that as yet any direct evidence has 
been offered that the electrical character of an atom is not an es- 
sential quality, but one that changes with circumstances. It ap- 
pears to be rather a matter of inference than of absolute demon- 
stration. 
It is the object of this memoir to furnish such direct evidence, 
and to show that chlorine, the substance which has given rise to 
* Communicated by the author. 
