ON PERCHLORIDE OF IRON. 
167 
ART. XL.— ON THE PREPARATION OF PERCHLORIDE OF 
IRON. 
The sesquichloride or perchloride of iron exists in the 
anhydrous state and in the state of hydrate. 
There are two processes for obtaining the anhydrous salt. 
The first consists in putting iron filings into a luted glass or 
porcelain tube, placed in a furnace, the tube being suffi- 
ciently long to project some distance beyond the furnace, and 
the iron being kept in that part of the tube directly exposed 
to the heat. When the apparatus has been thus arranged, 
the tube is heated to a temperature below that of red heat, 
about 752° Fahr., and then a current of dry chlorine is made 
to enter at one end of the tube. The chlorine is rapidly ab- 
sorbed, the iron becoming incandescent, while copious va- 
pors of sesquichloride are formed, which condense in the 
form of scales, having a violet color and metallic lustre in 
the cool part of the tube. 
The second process consists in saturating commercial hy- 
drochloric acid with hydrated peroxide of iron, either in 
the dry or moist state. The solution is commenced without 
heat ; it is afterwards continued with the aid of a gentle 
heat: when the acid ceases to dissolve any more oxide, the 
liquor is filtered and evaporated to dryness in a porcelain 
capsule, taking care to moderate the heat and to stir con- 
stantly. The product of this operation is introduced into 
an earthen retort, and heated gradually, taking care not to 
apply any fire to the dome of the retort. Aqueous vapors 
are first disengaged ; when these cease to appear, a cork is 
loosely fitted to the mouth of the retort, and the heat is then 
increased until the bottom of the retort becomes nearly red 
hot towards the close of the operation. The anhydrous 
perchloride sublimes on to the dome and into the neck of 
