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

MOLYBDENUM COMPOUNDS FROM MOLYBDENITE. 227

strictions in the combustion tube so that at these points the

inside diameter is from 1.0 to 1.2 cm., while the right-hand

arm of the tube is 32 cm. and the left arm 60 to 70 cm. long.

I Hood

_ B a
Jj=» IP Z3
702 ->n. p-aBSS-^ Burner

Fig. 26.

Place about 6 g. of powdered molybdenum in the shorter arm,

and introduce carbon dioxide and hydrogen into the apparatus

until all the air has been replaced in the wash bottles and the

connections. Then close the pinch cock of the carbon dioxide

tube, and, while passing a slow current of hydrogen, heat the

molybdenum as strongly as possible with a row burner for one

or two hours, preventing loss of heat by using the asbestos

mantle. Drive out any condensed water through the open

end of the tube, C, by fanning with a Bunsen flame. Allow

the apparatus to cool completely while the hydrogen is still

passing. Meanwhile start the action in the chlorine generator.

Pass the chlorine gas through a wash bottle containing water,

and then through two others containing concentrated sulphuric

acid; at the outset, keep the rubber connector which admits to

the combustion tube closed by means of a pinch cock, and allow

the chlorine to escape as indicated through the side arm into the

ventilating flue. When the air has been completely driven out

of the evolution flask and from all the connections (which, with a

fairly rapid current of chlorine, requires about an hour), replace

the hydrogen in the combustion tube with carbon dioxide, and

then the latter with chlorine. The reaction begins either of

itself or on heating very gently with the row burner. Streams of

a dull-red vapor rise and condense beyond the constriction at B.

By heating the molybdenum gently with the row burner and