PHARMACEUTICAL NOTICES. 
93 
ART. XXIX. — PHARMACEUTICAL NOTICES. 
By William Procter, Jr. 
Donovan's Solution. 
The formula for Donovans's solution, as published by its 
author, and of which a copy is found in the United States 
Dispensatory, presents so complex an appearance in the 
way of fractions of a grain, that many apothecaries, not 
possessed of a delicate balance and weights are deterred 
from making it. 
Another objection is that a loss of iodine is occasioned by 
the exposure rendered necessary during the trituration of 
the three elements with the alcohol during the time that 
elapses before the combination is effected. The mercury 
rapidly acquires its dose of iodine, whilst the arsenic, which 
combines less readily, is liable to all the deficiency oc- 
casioned by vaporization. That this occurs is evident from 
a small quantity of arsenic left undissolved by the distilled 
water. The proportions in Donovan's formula are 6. OS 
grains of arsenic, 14.82 grains of mercury, and 49 grains 
of iodine, which are not exactly in atomic relation. In 
order that the preparation should be composed of one equiva- 
lent of each iodide, the numbers should be 5.5 arsenic, 
14.82 mercury, 46.09 iodine, so that there is one-tenth of 
an equivalent of the arsenical iodide in excess. It is hardly 
probable that any sensible variation would be observable 
in the medicinal action of the solution if the iodides were 
used in equivalent proportion ; and as their combining 
number is the same, the preparation of the solution may be 
much simplified. 
The aggregate of the solid contents of half a pint of 
Donovan's solution is 70 grains, which is composed of 33£ 
grains of biniodide of mercury and 36§ grains of sesqui-iodide 
of arsenic. If the formula was made to require 35 grains 
VOL. XIII. NO. II. 9 
