PREPARATIONS OF IRON. 
95 
ART. XV. — ON SOME PREPARATIONS OF IRON. 
By James Hopkins. 
{Extract from Inaugural Thesis.) 
Sulphate of Iron. All the pharmacopoeias give formulas 
for its preparation, but differ much in regard to the quanti- 
ties of the articles employed. Those of the United States and 
London direct eight ounces of iron and eight ounces of acid. 
To this there is no material objection; there is, however, an 
unnecessary excess of iron. I have found by experiment that 
eight ounces of acid are completely neutralized by four and a 
half ounces of iron. 
No more water should be used than is really necessary, as 
in proportion to the weakness of the solution the evaporation 
is prolonged; under any circumstances, water in weight equal 
to nine times that of the acid employed will be sufficient; and 
where a moderate degree of heat can be retained in the solu- 
tion until it is filtered, a still smaller quantity will answer. 
The effervescence generally ceases before the acid is en- 
tirely neutralized ; it may be renewed by a slight applica- 
tion of heat. If the solution contain but little sediment, it 
may be clarified quickly by passing it through a funnel, in the 
neck of which is slightly pressed a portion of cotton. 
The evaporation of the liquid requires some caution, for if 
it be exposed to too high a temperature it becomes charged 
with a reddish yellow precipitate, (the subsulphate of the per- 
oxide.) A long exposure to even a moderate temperature 
produces the same effect. It should be placed in a broad, flat 
dish, and submitted to an even temperature of about 180° of 
Fahrenheit; the crystals should be perfectly dried and put 
into a glass stoppered bottle. The French pharmacopoeia of 
Ratier asserts that the sulphate of iron (of commerce,) which 
contains the sulphates of copper and alumina, may be purified 
by boiling the solution with pure iron filings, straining and 
