This chemical test works equally well for the determination of sulfur but without addition of silver nitrate.
The sulfuric acid intermediate formed after reaction of sulfur with fuming nitric acid forms insoluble barium sulfate on addition of barium chloride.
The purpose of adding the nitric acid is to oxidise the carbon and hydrogen.
Even the oxidation of iodine by concentrated nitric acid happens only at high temperatures.
This test was invented by the German Chemist, Georg Ludwig Carius (1829–1875).