"Frothing" is another objectionable feature with many liquids.
The engine turned over and backfired, black smoke frothing out of the tail pipe.
And Marsh's test is very unmanageable with organic liquids on account of the uncontrollable frothing that takes place.
The verb is used for the creaming or frothing of liquids and of the suffusing of the skin with blood.
Yet frothing is not excessive, because the slag is not, as in common practice, locally chilled and made viscous by cold lumps of ore.
Boiled oil is prepared in a variety of ways - that most common being by heating the raw oil in an iron or copper boiler, which, to allow for frothing, must only be about three-fourths filled.
Moreover, since local cooling, with its consequent viscosity and tendency to froth, are avoided, the frothing is not excessive in spite of the rapidity of the reaction.