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

PREPARATION OF CHLORINE. 77B

brilliant, glistening leaflets falls into the bulb of the retort. Heat

the neck of the retort by fanning it with a second and larger flame

until all of the ferric chloride is sublimed into the bulb. Tap the

vertical tube lightly so that any of the product condensed in it

will fall back into the retort.

At the end of the experiment shake the product, which is very

hygroscopic, directly from the retort into a dry, wide-mouthed,

glass-stoppered bottle. The preparation keeps well if the stopper

is made air tight with a little vaseline.

Preparation of Chlorine.

Large quantities of chlorine may be prepared by the oxidation

of hydrochloric acid with pyrolusite. Half fill a round-bottomed

flask of from 1.5 to 2 liters capacity (cf. Fig. 14, p. 77F) with lumps

of pyrolusite, and close the flask with a two-holed stopper;

1

through one hole insert a thistle tube, which serves as a safety

tube, and must extend 20 to 30 cm. above the top of the flask

and nearly to the bottom inside. Through the other hole insert

a short delivery tube bent at a right angle. To cause the evolu-

tion of chlorine, pour concentrated commercial hydrochloric acid

through the thistle tube until the pyrolusite is just covered, and

heat the mixture gently on a Babo funnel; regulate the rate at

which the gas is generated by altering the height of the flame

under the evolution flask. A single charge of pyrolusite is suffi-

cient to react with several refillings of the acid. Wash the gas

with water, and dry it (if necessary) by passing it through one or

two bottles containing concentrated sulphuric acid.

It is very convenient to use the dry liquid chlorine which

can be purchased in steel cylinders under pressure; but this

is only to be recommended when large amounts are frequently

used.

When it is desired to prepare a definite amount of chlorine, an

excess of hydrochloric acid can be decomposed by means of a

(^1) Cork stoppers can be made air tight by immersing them in molten paraffin
at about 150°. Such a paraffined stopper should be tightly wired in place to
prevent it from popping out when the flask is heated.