EPURENE.--A purifying material to which the name of epurene has been
given has been described, by Mauricheau-Beaupre, as consisting of a
mixture of ferric chloride and ferric oxide in the proportion of 2
molecules, or 650 parts, of the former with one molecule, or 160 parts,
of the latter, together with a suitable quantity of infusorial earth. In
the course of preparation, however, 0.1 to 0.2 per cent. of mercuric
chloride is introduced into the material. This mercuric chloride is said
to form an additive compound with the phosphine of the crude acetylene,
which compound is decomposed by the ferric chloride, and the mercuric
chloride recovered. The latter therefore is supposed to act only as a
carrier of the phosphine to the ferric chloride and oxide, by which it is
oxidised according to the equation:
8Fe_2Cl_6 + 4Fe_2O_3 + 3PH_3 = 12Fe_2Cl_4 + 3H_3PO_4.
Thus the ultimate products are phosphoric acid and ferrous chloride,
which on exposure to air is oxidised to ferric chloride and oxide. It is
said that this revivification of the fouled or spent epurene takes place
in from 20 to 48 hours when it is spread in the open in thin layers, or
it may be partially or wholly revivified _in situ_ by adding a small
proportion of air to the crude acetylene as it enters the purifier.
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