124 On Iodine. [Ave. 
centre of the one being the heart, and of the other the head) ; and 
that there is scarcely any point of the body which this circle does 
not involve and rest on, since from almost every point ascends 
impression to the cerebrum by a nerve of sensation, the anterior 
nervous roots, and the anterior columns of the spinal marrow ; and 
to each returns expression from the cerebellum by the posterior 
columns, the posterior nervous roots, aud the nerves of volition. 
Nothing perhaps more than this beautiful correspondence between 
the vital and intellectual systems is calculated to raise the mind to 
him of whom the wisdom is testified by all that lives, from the most 
simple to the most‘complex of beings—from the polyp which can 
boast no other organ than a stomach, to man who has an intellectual 
system thus wonderfully complex and beautifully symmetrical. 
Having, Sir, been, long engaged in dissections of the brain of 
fishes, amphibia, and birds, in order further to illustrate and esta- 
blish these important truths, I shall, on their conclusion, be happy 
to communicate them through the medium of your Journal. But 
you will excuse my in future not replying to statements so hastily 
made as those in answering which I have been reluctantly com- 
pelled to occupy so much of your present number—statements in 
which a confident reference is made to a book for a doctrine which 
that book, on the contrary, most pointedly contradicts ; and to the 
animal body for a structure which has no other foundation than in 
the writer’s mistaking the branches of a nerve for its roots. 
Iam, Sir, with great respect, 
Your most obedient servant, 
ALEXANDER WALKER, 
Articite VII. 
A Memoir on Iodine. By M. Gay-Lussac. 
(Continued from vol. v. p. 413.) 
Observations on Chlorine. 
Tue analogy which I have established between chlorine, sul- 
phur, and iodine may serve to throw some light on some of the 
combinations of chlorine, as I shall endeavour here to show. 
M. Thenard and myself were the first persons who showed by a 
numerous series of experiments, that oxymuriatic acid might be 
considered as a simple substance, as there was no direct means of 
showing the presence of oxygen in it. We had even given this 
hypothesis at full length, ina memoir which we read to the Society 
of Arcueil, on the 26th of February, 1809; but it appeared so 
extraordinary, that M. Berthollet prevailed upon us to state it with 
the greatest reserve. In fact, though Davy has announced in his 
memoir on oxymuriatic acid, that this hypothesis had been ad~ 
vanced by Scheele, it was entirely new, and it appeared extray 
