Carius method for determination of the halogens and sulphur.
When strongly heated iron inflames in oxygen and in sulphur vapour; it also combines directly with the halogens.
Halogens do not act directly on water, hence we may not properly speak of halogen substitution products.
It is rapidly oxidized on exposure, is a strong reducing agent, and reacts vigorously with the halogens.
Substances which, like the halogens, appear to form substitution compounds, e.g.
The lignone complex reacts, by its unsaturated groups, with the halogens.
The process is therefore adapted to the simultaneous estimation of carbon, hydrogen, the halogens and sulphur.
The halogens may be estimated by ignition with quicklime, or by heating with nitric acid and silver nitrate in a sealed tube.
Halogen acids convert it into monohalogen fatty acids, and the halogens themselves convert it into dihalogen fatty acids.