Eitner and Keppeler have proposed to burn the acetylene on which the
estimation is to be made in a current of neat oxygen. But this procedure
is rather inconvenient, and by no means essential. Lidholm liberated
acetylene slowly from 10 grammes of carbide by immersing the carbide in
absolute alcohol and gradually adding water, while the gas mixed with a
stream of hydrogen leading to a burner within a flask. The flow of
hydrogen was reduced or cut off entirely while the acetylene was coming
off freely, but hydrogen was kept burning for ten minutes after the flame
had ceased to be luminous in order to ensure the burning of the last
traces of acetylene. The products of combustion were aspirated through a
condenser and a washing bottle, which at the close were rinsed out with
warm solution of ammonia. The whole of the liquid so obtained was
concentrated by evaporation, filtered in order to remove particles of
soot or other extraneous matter, and acidified with nitric acid. The
phosphoric acid was then precipitated by addition of ammonium molybdate.
J. W. Gatehouse burns the acetylene in an ordinary acetylene burner of
from 10 to 30 litres per hour capacity, and passes the products of
combustion through a spiral condensing tube through which water is
dropped at the rate of about 75 c.
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