The simultaneous system of two quadratic forms ai, ay, say f and 0, consists of six forms, viz.

Heating or exposure to sunlight reduces it to the red oxide; it fires when ground with sulphur, and oxidizes ammonia to nitric acid, with the simultaneous formation of ammonium nitrate.

If the two things are different, they are either simultaneous or in succession.

A simultaneous insurrection at Massa - Carrara was crushed with similar vigour.

In Transylvania, however, the common peril evoked by the Turkish incursion and a simultaneous rising of the Vlach peasantry had knit together the jarring interests of Magyars, Saxons and Szeklers, a union which, under the national hero, the voivode Janos Hunyadi, was destined for a while to turn the tide of war.