601 
NOTES ON THE B. P. SOLUTIONS OF IODINE, AND OTHER. 
PHARMACOPCEIAL PREPARATIONS. 
BY WILLIAM MARTINDALE, 
DISPENSER, AND TEACHER OF PHARMACY TO THE UNIVERSITY COLLEGE HOSPITAL. 
There are three solutions of iodine in the Pharmacopoeia,—the tincture, 
liquor, and liniment. 
Tinctura Iodi .—The formula for this is the same as that of B. P. 1864, and 
the quantity of iodine is equal to that in tinctura iodinii composita, P. L. 1851, 
but the iodide of potassium is only one-fourth. This quantity of iodide of 
potassium does not seem to hoof any practical utility that I can conceive,—in 
fact, for one purpose for which it is used, it is a decided objection. The quan¬ 
tity of the iodide in the London tincture, and it was much in excess for the pur¬ 
pose, rendered it miscible with water, but that in the present tincture does not, 
as on its addition to water, the bulk of the iodine is precipitated.* 
If it be necessary, and for internal administration it is necessary that it 
should mix with water, why not make it with water in the first instance, more 
especially as it has been stated that a spirituous solution of iodine undergoes de¬ 
composition on being kept ? I find practically that 23 grains of the iodide will 
dissolve 20 grains of iodine in 1 ounce of water. A little excess of the iodide 
renders the iodine more readily soluble, as in liquor iodi, B. P., 30 grains are 
employed to dissolve 20 of iodine in the same quantity of water. This liquor is 
known as Lugol’s solution, when diluted, it is the best preparation for injecting 
in hydrocele, etc. 
I would suggest the use of two liquors, one to be called liquor iodi (in place 
of the tincture), and the other liquor iodi fortior. 
The case in which the presence of the iodide in the tincture is objectionable, 
is, when it is added to boiling water, to yield the vapour of iodine for inhalation ; 
for this] purpose the iodine would be more completely vaporized if not held in 
solution by the water. The old Edinburgh simple tincture of iodine answers 
best for this purpose. 
For external use spirituous solutions have this disadvantage—they have not 
u body” enough, as the spirit volatilizes too quickly, leaving the iodine in a free 
state upon the skin, in which condition little of it is either absorbed, or produces 
any counter-irritation, as it, too, becomes quickly vaporized. 
Iodine and Oil of Tar .—A solution, or rather a mixture, as it is not a mere 
solution, of 1 part of iodine with 4 of light oil of wood tar, makes a useful ap¬ 
plication. In mixing the iodine and oil of tar great heat is evolved—part of the * 
oil is oxidized aud becomes resinous. This resinous portion, being held in solu¬ 
tion in the excess of oil, on applying the mixture to the affected part, acts like 
a varnish, and prevents the vaporization of the iodine. This application is 
found to be very useful in ringworm and similar skin affections. 
Linimentum Iodi .—When iodine is intended to produce counter-irritation, or 
promote the absorption of glandular swellings, this is a suitable application, but 
for the reasons I have stated, it has not “ body” enough—much of the iodine is 
vaporized and produces no effect; moreover, when this liniment is applied re- 
* In all proportions between one part of the tincture, and from three to forty of water, this 
precipitation or crystallization of the iodine takes place, but it is most evident on mixing one 
part of the tincture with six of water. My attention has been frequently drawn to this 
fact when rinsing with water a measure glass that has contained the tincture, the free iodine 
causes the glass to have a greasy appearance, in which conditiqn it has a repulsion for water. 
On adding the liniment of iodine to water, a still more abundant separation of the iodine 
occurs. 
YOL. XI. 2 R 
