N:NCl + 2H

2

O.

Diazo-azo-benzene-chloride.

When this compound is combined with naphthol diazo-azo dyes are produced.

C6H5N:NC6H4N:NC10H6OH. Benzene-azo-benzene-azo-naphthol.

The molecular weights of the bases, phenols and chemicals employed are the following:—

1. Hydrochloric acid, HCl—36.5. 2. Caustic soda, NaOH—40. 3. Nitrite of soda, NaNO2—69. 4. Acetate of soda, NaC2H3O23H2O—136.

1. Commercial hydrochloric acid at 32° Tw. contains about 365 grams of HCl in a litre, or 3½ lb. in a gallon.