550 
PREPARATION OF LIQ. FERRI ET PERCHLOR., P.R, 
The process is as follows :— 
Take of Iron Wire, two ounces. 
Hydrochloric Acid, ten fluid ounces. 
Nitric Acid, six fluid drachms. 
Distilled Water, seven fluid ounces. 
Dilute the hydrochloric acid with five ounces of the water, and pour the 
mixture on the iron wire in successive portions, applying a gentle heat when the 
action becomes feeble, so that the whole of the metal may be dissolved. To the 
nitric acid add the two remaining ounces of the water, and having poured the 
mixture into the solution of iron, evaporate the whole until the bulk is reduced 
to ten fluid ounces. 
The product is described as an orange-brown solution, without smell, but 
possessing a strong styptic taste, miscible with water and alcohol in all pro¬ 
portions. Diluted with water, it is precipitated white by nitrate of silver, and 
blue by the ferro-cyanide of potassium, but not by the ferrid-cyanide. 
“Tests, specific gravity 1-388. A fluid drachm, diluted with two fluid 
ounces of water, gives, upon the addition of an excess of solution of ammonia, a 
reddish-brown precipitate, which, when well washed and incinerated, weighs 
15-62 grains.” 
The first and most important question which falls to be answered is, Is the 
process theoretically correct ? In order to arrive at a just conclusion on this 
point, we must first ascertain the nature of the chemical changes which are 
effected during the operation. The decomposition is as follows :— 
6 Fe + 9 H Cl + N0 5 =. 3 F 2 Cl 3 -f 3 HO + N0 2 
The quantities of the various ingredients actually required may be demon¬ 
strated as follows:— 
C Fe + 9II Cl + NQ. 
16S grains of "28^ grains of 54 grains of 
Iron. Hyd. Acid Gas. Anhydrous Nitric Acid. 
Deduced by proportion for the Pharmacopoeia formula, the quantities are as 
follow :— 
Iron, 875 grains ; hydrochloric acid gas, 1,711 grains ; and anhydrous nitric 
acid, 281 grains. In round numbers, the formula would be—iron, two ounces ; 
hydrochloric acid, sp. gr. 1-17, nine fluid ounces and six fluid drachms. Nitric 
acid, sp. gr. 1-5, four fluid drachms and eighteen minims; so that the formula 
given in the British Pharmacopoeia is theoretically correct, and a little more.* 
The next consideration, and the one which is perhaps of the most importance 
to us is, Is the process practically an efficient one ? It is on this point that the 
opinions of practical men differ. The widely different results obtained by dif¬ 
ferent operators is not at all surprising when we consider that many of them, 
though expert enough pharmaceutists, are not by any means expert chemical 
manipulators. The process is a chemical one, and while the compilers of the 
Pharmacopoeia have been minute almost to a fault in the description of many 
of the chemical operations contained in that work, they have erred the other 
way in the one under consideration. 
Before going further, I may as well describe what takes place during the 
progress of the operation. The solution of iron having been filtered, is of a 
very fine grass-green colour. They have omitted to direct filtration; but 
filtered it must be, in order to procure a really elegant product. Even the finest 
specimens of iron contain carbon, which shows itself as a black flocculent sedi- 
* My calculations were made before the appearance of the February number of the c Phar¬ 
maceutical J our mil/ but my figures differed slightly from those given by Dr. Attfield, 
having calculated from different data. I have adopted his, as being the most likely to be 
correct. 
