PREPARATION OF BESTUCHEFF's TINCTURE. 
325 
of aqua regia, and then to evaporate the superfluous acid by means 
of a sand bath. The sesqui-chloride thus obtained is employed in 
the preparation of " Bestucheff's tincture," by dissolving one 
ounce of it in an ounce of water, adding twelve ounces of ether 
and agitating, then decanting the ethereal solution, and finally 
mixing it with four times its bulk of alcohol. 
Having had frequent occasion to prepare this tincture as well in 
Germany as in this city, it may not be unsuitable if I give here 
the formula for its preparation, which seems to me the most con- 
venient, as well as my reasons for thinking so. 
The sesqui-chloride of iron may be obtained in a pure and neu- 
tral state by passing a current of chlorine gas through a solution 
of proto-chloride of iron, until a solution of the red ferrocyanide 
of potassium of Gmelin no longer produces a blue precipitate, and 
then evaporating the solution by means of a water bath. In this 
manner the salt can readily be obtained in a crystalline form. One 
ounce of the crystals thus obtained is to be dissolved in twelve 
ounces of ether, if we retain the alleged proportions, mixed with 
four times its bulk of alcohol, and finally bleached by exposing it 
to the direct line of the sun. 
The Prussian Pharmacopoeia of 1846 gives the following pro- 
portions :— One drachm of the sesqui-chloride of iron, or two 
drachms of the aqueous solution, one fluid ounce of ether, and three 
fluid ounces of alcohol. 
Here we have to notice, — 1st, That it is preferable to take 
ether and alcohol by weight rather than by measure, since their 
volume is very much influenced by the temperature, which may 
range from 32° to 60° or 80°. 
2nd, That the sesqui-chloride, prepared with nitro-muriatic acid, 
is not so easy to obtain in crystals, in consequence of the adhering 
nitro-muriatic acid, which is always retained in small quantities. 
On the other hand, by drying the salt you will, in almost every 
case, spoil a quantity of it by driving off too much of the acid. 
3rd, That the sesqui-chloride of iron, if in crystals, is easily and 
wholly soluble in ether, while the aqueous solution of it is but 
partially so, a portion being decomposed, as is evidenced by the 
solution becoming muddy. The ethereal solution, if prepared in 
the last mentioned manner, must be of uncertain strength, which 
is avoided by the first. 
