rate are essential for a good product.

A large vessel is needed for the reaction, as the nitroso-b-naphthol
separates in a finely divided condition and there is some
tendency to foam.

The final air-dried product is pure except for its moisture content,
as is shown by the fact that on drying _in vacuo_ it has a very good
melting point. A sample of Kahlbaum's nitroso-b-naphthol melted
at 101--105.


3. Other Methods of Preparation

Nitroso-b-naphthol has been made by the action of hydroxylamine
hydrochloride on b-naphtho-quinone-chlorimide;[1] by the action
of sulfuric acid upon a solution of potassium or sodium nitrite
and the sodium salt of b-naphthol;[2] by the action of sodium nitrite
upon an alcoholic solution of zinc chloride and b-naphthol;[3]
by the action of sodium nitrite upon b-naphthol suspended in zinc
sulfate solution;[4] by the action of nitrous acid on b-dinaphthol
methane;[5] and by the action of nitrosyl sulfate upon the sodium
salt of b-naphthol.[6]

[1] Ber. 27, 241 (1894).

[2] Ber. 8, 1026 (1875); 27, 3076 (1894); J. Chem. Soc. 45, 295 (1884).

[3] Ber. 18, 705 (1885).