STRENGTH. OF DIFFERENT SAMPLES OF DONOVAN’S SOLUTION. 213 
1. 
3. 
Donovan. 
Dublin Pliarm. 
Arsenic Metal . . , 
. 6-0.8 
Pure Arsenic.... 
.- 6- 
Mercury 
. 14-82 
Mercurv. 
. 16- 
Iodine . 
Pure Iodine .... 
. 501 
Alcohol 
. q.s. 
Water. 
Water. 
Alcohol. 
2. 
4. 
Pereira. 
Soubeiran. 
Arsenic 
. 6-08 
Teriodide of Arsenic 
. 35 grs. 
Mercury 
. 15-38 
Biniodide of Mercury . 
. 35 ,, 
Iodine . 
. 50- 
Water.. 
. 8 oz. 
Alcohol 
Boiling Water . . . 
. 8 oz. 
And a writer in the ‘ Pharmaceutical Journal,’ with the view of avoiding the 
inconvenience resulting from the noncombination of the iodine with the 
arsenic, which, he states, frequently occurs, gives the following:— 
5. 
Arsenious Acid.7-92 
Iodide of Mercury.36 24 
Hydriodic Acid. 30 49 
Distilled Water.8 oz. 6 drs. 
“ Mix and make up the solution to its original volume.” “ The hydriodic acid is best 
prepared by decomposing a known weight of iodide of barium with sulphuric acid.” 
Although the three first of these processes were recommended by very 
high authority, it will be perceived that they vary in the proportions of their 
ingredients ; and, as it is admitted that there is some patience required and 
difficulty in effecting the complete combination of the arsenic with the iodine, 
M. Soubeiran proposed the direct union of the iodides of the metals. But, 
independently of the deviation from the strength originally contemplated by 
Dr. Donovan, M. Soubeiran’s form is open to the objection that the iodides 
of mercury and arsenic vary in the proportions of moisture they contain, and 
thus lead to varying results. To alter a mode of manipulation may be per¬ 
fectly legitimate, but to alter proportions of a preparation intended for public 
use, without leave of the introducer, is scarcely right. Great confusion has 
arisen in pharmacy from such a practice, and many very excellent prepara¬ 
tions have been pronounced a failure, and been superannuated, owing to the 
difficulty entailed on a dispenser in attempting to determine which of many 
under one name is intended by the physician, and thus those, which for many 
reasons he may not see fit to use, become shelved. Dr. Donovan had in 
view a preparation which he seemed to have perfected, and the formula for 
which he most liberally published. He admits the difficulty of producing 
the combination with celerity, but he is fairly entitled to claim for a process 
which, if an alteration be made, shall not involve a variation in the propor¬ 
tions which he sets forth. When Dr. Donovan first made the solution he 
found that it generally proved to be of a very pale yellow, and then only 
when seen in large quantity, sometimes being as pale as water. W r hen a few 
grains of iodine were added it became yellow ; but when exposed to ordinary 
daylight it resumed its original colourless appearance ; and further additions 
of iodine presented the same phenomenon. Dr. Donovan’s formula is entitled 
to all commendation ; and, provided the materials are pure, and with due 
attention to the manipulation, a preparation of definite composition, and 
having invariable properties, may be obtained. Thus :— 
