but I.
Remsen and his pupils (_Amer. Chem. Journ._, 1888, 9, pp. 389 et seq.)
have shown that the main product of this reaction is usually a
phenolic ether. This reaction has also been investigated by A.
Hantzsch and E. Jochem (_Ber._, 1901, 34, p. 3337), who arrived at the
conclusion that the normal decomposition of diazonium salts by
alcohols results in the formation of phenolic ethers, but that an
increase in the molecular weight of the alcohol, or the accumulation
of negative groups in the aromatic nucleus, diminishes the yield of
the ether and increases the amount of the hydrocarbon formed. The
replacement is more readily brought about by the use of sodium
stannite (P. Friedlander, _Ber._, 1889, 22, p. 587), or by the use of
a concentrated solution of hypophosphorous acid (J. Mai, _Ber._, 1902,
35, p. 162). A. Hantzsch (_Ber._, 1896, 29, p. 947; 1898, 31, p. 1253)
has shown that the chlor- and brom- diazoniumthiocyanates, when
dissolved in alcohol containing a trace of hydrochloric acid, become
converted into the isomeric thiocyanbenzene diazonium chlorides and
bromides. This change only occurs when the halogen atom is in the
ortho- or para- position to the -N2- group.

_Metallic Diazo Derivatives._--Benzene diazonium chloride is
decomposed by silver oxide in aqueous solution, with the formation of
_benzene diazonium hydroxide_, C6H5.N(OH):.N. This hydroxide, although
possessing powerful basic properties, is unstable in the presence of
alkalis and neutralizes them, being converted first into the isomeric
benzene-diazotic acid, the potassium salt of which is obtained when
the diazonium chloride is added to an excess of cold concentrated
potash (A. Hantzsch and W. B. Davidson, _Ber._, 1898, 31, p. 1612).
_Potassium benzene diazotate_, C6H5N2.OK, crystallizes in colourless
silky needles. The free acid is not known; by the addition of the
potassium salt to 50% acetic acid at -20 deg. C., the acid anhydride,
_benzene diazo oxide_, (C6H5N2)2O, is obtained as a very unstable,
yellow, insoluble compound, exploding spontaneously at 0 deg. C. Strong
acids convert it into a diazonium salt, and potash converts it into
the diazotate. On the constitution, of these anhydrides see E.
Bamberger, _Ber._, 1896, 29, p. 446, and A. Hantzsch, _Ber._, 1896,
29, p. 1067; 1898, 31, p. 636. By the addition of the diazonium salts
to a hot concentrated solution of a caus