TIN TETRACHLORIDE. 79
sure gives good results, provided the two temperatures compared
are not far from one another. Boiling-point of bismuth bromide,
466
0
.
1- Tin Tetrachloride.
Make use of the same apparatus as described under the prep-
aration of sulphur chloride (Fig. 14, p. 77F). Place 60 g. of tin
in the retort, and heat it by placing a Bunsen flame underneath.
After the tin is melted pass a rapid current of chlorine, allowing
it to play directly on the surface of the metal. Liquid tin tetra-
chloride, which is colored yellow by dissolved chlorine, collects
in the receiver. When the metal in the retort has all disappeared,
add some tinfoil to the distillate in the receiving flask, stopper the
latter, and allow it to stand until the next day in order that the
dissolved chlorine may all react with the tin.
Place the crude product together with a little tinfoil in a 100 c.c.
distilling flask, provided with a side-arm condenser (Fig. 7).
Fit a thermometer in the neck of the flask, and distil the liquid at
the hood, rejecting the first few drops which pass over. If the
distillate is not perfectly colorless, allow it to stand over night with
more tinfoil and repeat the distillation. Boiling-point, 113.5° to •
114°. Preserve the preparation in a sealed vessel.
When exposed to the atmosphere, tin tetrachloride absorbs
water and soon becomes changed to the solid white hydrate.
Tin tetrachloride can, like titanium tetrachloride, be transformed
into the corresponding sulphide (cf. Titanium Disulphide, No. 58).
The formation of colloidal stannic acid from tin tetrachloride is
discussed under Purple of Cassius, No. 25.
A very convenient method for making tin tetrachloride at room
temperatures from tin and dry chlorine has been described by
R. Lorenz.
2
Fill a test tube, about 4 cm. wide and 40 mm. long,
about one-quarter full of dry granulated zinc. Place a cork in the
tube, carrying tubing for the introduction of dry chlorine and also
for the escape of gas. Fasten the tube in an upright position and
introduce chlorine with the tube reaching nearly to the bottom of
the test tube. At fir'st introduce the gas slowly, and later, when
liquid stannic chloride has formed, increase the rate of flow.
(^1) Author's observation: Victor Meyer found 453° with an air thermometer.
Ann. 364, 122 (1891).
(^2) R. Lorenz, Z. anorg. Chem., 10, 44 (1895).