Laboratory Methods of Inorganic Chemistry, 2nd English Ed. 1928

77E HALOGEN COMPOUNDS.

are obtained, together with a darker powder of a more brownish

shade which under the microscope is shown to be crystalline.

Collect the two forms separately. Chromium trichloride is, on

account of its slow rate of solution, practically insoluble in water.

It is difficult to clean the porcelain tube after this experiment.

Stopper it at one end, and fill it with commercial, concentrated

hydrochloric acid to which a little ferrous sulphate has been

added, and let it stand. Dependent preparations: Chromium

Nitride (No. 62), Hexamminechromic Nitrate and Chloropen-

tamminechromic Chloride (No. 140).

45. Sulphur Chloride, S 2 C1 3.
    Of the chlorides of sulphur, S2CI2 is the only one stable at the laboratory
    temperature. The chloride SCI4 is a yellowish-white substance which melts
    at —30° and decomposes at a few degrees above the melting-point. The
    dark red compound SCI2 exists in mixtures of S2CI2 and CI2.

Connect a tubulated retort (Fig. 14) of 250 c.c. capacity with

a condenser, an adapter, and a suction flask which serves as a

receiver; from the side arm of the latter, lead a glass tube to

the ventilating flue. Fill the retort with 100 g. of flowers of

sulphur, and heat it upon a Babo funnel, or, better still, in a

nickel air-bath, to a temperature of from 200° to 250°. Conduct

into the retort a rapid current of chlorine, which has been

washed once with water and once with sulphuric acid. The sul-

phur chloride that is formed distils completely into the receiver;
a slight blackish coating which remains behind is due to impurities

in the sulphur. The operation requires about four hours.

To the crude product thus prepared, add 10 to 15 g. of sulphur

which combines with the excess of chlorine. Distil the sulphur
chloride from a fractionating flask provided with a condenser

and a receiver, and if more than a small amount passes over

before a temperature of 130° is reached, pour it back into the

flask and add more sulphur. Then distil again, rejecting the
portion that passes over below 134°, and collecting as pure pro-

duct the distillate between 137° and 138°. Only towards the

end of the process does the temperature rise a few degrees above

this point, due to superheating of the vapors. The excess of
sulphur remains behind in the flask. The preparation may be