129 
ON SYEUP OF PHOSPHATE OF lEON. 
BY CHARLES UMNEY, F.C.S. 
Syrup of pliospliate of iron was first introduced to the profession as a 
remedial agent, in 1851, by Dr. Eouth, in a communication to the Medical 
Society; its mode of preparation was subsequently given by Mr. Greenish, 
at a meeting of the Pharmaceutical Society. 
Dr. Eouth’s process for the formation of the syrup consisted in first 
making superphosphate of iron, by dissolving phosphate of iron in boiling 
metaphosphoric acid, and of this salt making a syrup. The syrup, however, 
when made in this manner, was found to be an unsatisfactory preparation, 
yet it continued to be prescribed until 1860, when the subject was investi¬ 
gated by Mr. S. Gale, whose successful experiments resulted in the produc¬ 
tion of a syrup uniform in strength and in the main satisfactory. It was 
from his formula that that of the British Pharmacopoeia was framed. But 
the preparation in question has been found to gain a reddish colour by age, 
which renders it unsightly, and possibly less efficacious. It was to ascer¬ 
tain the cause, and, if possible, to prevent this change, that I made the follow¬ 
ing experiments. 
The first opinion one would naturally form would be, that the change of 
the syrup from white to reddish-brown was due to the partial or entire per¬ 
oxidation of the iron present, and that the component parts of the syrup had 
possibly had a material influence in either setting up or assisting this decom¬ 
position. The only bodies present in the syrup being phosphoric acid and 
sugar, the latter probably would be the body taking any part in setting up a 
direct change; as phosphoric acid is one of the most stable acids, and not 
likely under such circumstances to become reduced and impart its oxygen to 
the protosalt of iron. The supposed influences most likely to aid in peroxi¬ 
dation or formation of other bodies, would be air and light. 
With these hypotheses as a starting-point, my experiments were conducted 
with a view, if possible, to prove that such suppositions were not unfounded, 
but really existed. I accordingly made the syrup according to the British 
Pharm. formula, taking care to well wash the precipitated phosphate of iron, 
at the same time avoiding exposing it to the air any more than necessary. 
The syrup being colourless and transparent, I placed it in selected bottles of 
dark blue and also of a light green colour; these were arranged as follows, 
and any change undergone by them was carefully noted through a period of 
five months :—■ 
(«) One of each of the coloured bottles was placed in the light of an 
ordinary window (with a north-eastern aspect), being quite full to the cork. 
The change in colour was very slight; the syrup in the green bottle, 
however, seemed to be much darker than that in the blue : upon testing 
it I found oxidation had taken place to the extent of 13'9 per cent, in the 
green, but in the blue onl)'' very slightly. 
(5) Two corresx)onding ones were also upon a roof, exposed to the direct 
rays of the sun. 
These had not gained colour even in five months, neither was there a 
perceptible difference between the blue and the green: upon testing these 
oxidation was found to have taken place only slightly. From this it 
would seem that direct light exerted somewhat less influence over the 
syrup than the light transmitted through the window. 
(e) A bottle was also enveloped in dark blue paper. 
This was scarcely altered, and had become to a small degree only 
oxidized. 
VOL. YIII. 
K 
