CHANGE IN TINCTURE OF IODINE. 
55 
the use of iodine ceased to exist, but on the other hand, it 
has been found, that weak and debilitated patients improved 
in appetite and condition, and young females acquired im- 
proved colour, increased developement of the breasts, and 
regularity of the natural economy, in proof of the beneficial 
action of the medicine. I have taken a review of these cir- 
cumstances, which must be in the recollection of most medical 
men, in order to establish the great difference which exists 
between the action of iodine when administered in the solid 
state, and in the slate of perfect solution. I now pass to 
the examination of the mixture employed by M. Velpeau 
in the treatment of hydrocele. 
I will first consider the case of tincture of iodine recently 
prepared, such as that which I present to the Academy, 
which was made three days ago, according to the directions 
of the Codex, by dissolving, without heat, one part of iodine 
in twelve parts of spirit, sp. gr. .848. If this tincture be 
mixed with twice its weight of water, the iodine will be 
almost entirely precipitated in the form of black particles, 
easily separating by repose, and the supernatant liquid will 
be almost colourless. In what way should this liquid be 
taken? If the clear and transparent part only be taken, it 
would probably produce only a slight stimulating effect, due 
principally to the spirit. If, on the other hand, the liquid 
be shaken up before taking it, the solid particles of iodine 
would be deposited on the coats of the intestinal canal, and 
would produce a degree of irritation that may not be free 
from danger. 
I will now consider the case of tincture of iodine which 
has been prepared four or five months. The following is 
the change which has taken place during this interval of 
time. One part of the iodine takes hydrogen from the alco- 
hol to form hydriodic acid, which unites with another por- 
tion of iodine to form ioduretted hydriodic acid, which gives 
no precipitate with water. On the other hand, the alcohol 
probably replaces the lost hydrogen by iodine, forming 
