Abstract: Protection of reactors, installed in an enclosed space, in which reactions take place with gases or volatile substances that are toxic and/or that can form an explosive mixture with air. The enclosed space is in open connection with means for passing any gases that may have escaped from the reactor through a liquid bath. The height of the liquid layer and the contents of the liquid bath are sufficient for the maximum possible amount of gas or volatile substance issued from the reactor to be dissolved, condensed, cooled off, inertized or be allowed to react. The liquid in the bath is water, lye, a salt solution, a cooled salt solution or heavy oil.