Olservations upon the Substance called Iode, or Iodine. 141! 
relaxes at stated intervals, so that a lady of fashion will be quite 
lively at a period when the regular citizen is seized with an irresisti- 
ble drowsiness. Habit will, moreover, so far divert the attention . 
from feelings generally causing action, that some persons can sleep 
while standing upright, or sitting on horseback. 
Upon the principles laid down, it will not be difficult to explain 
the operation of some other means by which sleep may be pro- 
moted or prevented. If the skull be laid open, and the cerebrum: - 
gently pressed upon, the animal sleeps from the retarded circula- 
tion and congestion induced. Opium and extreme cold, by im- 
pairing the sensibility of the vessels, diminish their resistance 
to the contained fluids, thus retarding circulation, and removing 
any opposition te congestion. Wine taken to excess, after a cer- 
tain period naturally disposes to sleep; for its primary effect being 
to increase cireulation, and accumulate blood in the head,—as 
soon as relaxation succeeds to inordinate action of vessels, the 
brain will be under every circumstance requisite for repose. Strong 
tea, both by its sensible impression on the mouths of the vessels, 
and by the relaxing effect of warmth, promotes secretion, unloads 
the vessels, and so far removes congestion, and quickens circula- 
tion, as to promote wakefulness. Opium indeed causes relaxa- 
tion of vessels, by impairing their sensibility; but imstead of in- 
¢reasing it usually diminishes secretion, and does not therefore 
remove congestion, but imereases it. Acids on the contrary, by 
promoting secretion, unload the vessels, atid, like tea, remove the 
soporific effects of opium. 
Such are the very numerous facts referable to Dr. Park’s prin- 
ciples ; and should any material points have been passed over, 
‘there can be little doubt that they also would reduce themselves 
to the same explication. He has extended his researches on this 
head to the phenomena of Dreaming, Incubus, and Seomnambu- 
lism. 
XXVIII. Further Observations concerning the Production of the 
singular Substance called Iode, or Iodine ; easy Methods of 
obtaining it; with Remarks on the comparative Nature of 
Kelp, as far as it regards the rapar asin of lode. By 
Freprick Accum, Operative Chemist, © 
Compton Street, oN Feb. 6, 1814. 
Sins,— 1 nz obliging manner in which you have noticed in 
your Magazine for "January last, the observations which I com- 
municated to you, concerning the method of preparing iode, 
induces me to send a few additional remarks on the same subject, 
; wiih I flatter myself may prove useful to some of your reat es 
pon 
