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

PHOSPHORUS PENTASULPHIDE. 85

escape. Allow the apparatus to cool completely, and remove the
preparation by the aid of a glass rod or a wire, after cutting the

tube, if necessary, into several sections. The preparation should

be protected from moisture, best by keeping it in a sealed tube.

Yield, slight.

(c) Sulphides.

54. Phosphorus Pentasulphide;' Thermoelectric Determination
    of the Bolling-Point.
    Mix 176 g. of flowers of sulphur with 62 g. of dry red phosphorus;

if the phosphorus is moist, it should be washed with hot water,

rinsed on a filter several times with water, then with alcohol, and
dried in the hot closet.

Clamp a 750 c.c. round-bottomed flask to a ring-stand, under the
hood, at a suitable height above a Bunsen burner. Introduce a

spoonful of the above mixture into the flask, and after replacing

approximately all of the air with carbon dioxide, heat until a

reaction begins. Then remove the burner at once, and add
spoonful after spoonful of the powder so that each portion imme-

diately enters into reaction; toward the end heat the flask from

time to time with the burner. Take care that neither the powder

in the spoon nor the supply of unused material catches fire; keep

a supply of sand on hand to throw on the blaze, and a pan to catch

the liquid, in case the flask should break and its burning contents

run out. Usually the preparation can be carried out without

accident. After cooling, break the flask, and collect the gray and

somewhat hygroscopic crude product.

Purify the substance by distilling it from a small, wide-necked,

plain retort, rejecting the first few drops of distillate and collecting

the main portion in a dry flask. To retain the heat, fold a piece

of asbestos paper into a cone and place it over the neck and bulb

of the retort. The distillate solidifies into a light-yellow, amor-

phous mass. Break the flask and transfer the product, after

removing any fragments of glass, to a bottle which can be tightly

stoppered. Yield, about 180 g.

A part of the preparation can be further purified by crystalliza-

tion from carbon bisulphide. Place the material in a Soxhlet

thimble, extract it for several days with carbon bisulphide in an

Cf. A. Stock, Bcr. 41, 563 (19081.