76

THE TRUE THEORY OP MAKING SAFES FIRE-PROOF.

have given this point much consideration, and havecome to the conclusion, that such a contrivancedoes not add anything to the fire-resisting capabilityof a safe. I cannot agree with the writer of the

Fig. 44.—Section of fire-proof Safe,with double chambers,a, The outer plate.b b, The two chambers.c, The inner plate or lining.

Fig. 45.—Section of fire-proof Safe,with triple chambers.a, The outer plate.bbb, The three chambers.c, The inner plate or lining.

before-mentioned article in the Edinburgh Courant,that “ the alkalis of the outer chamber are almostentirely dissolved and evaporated before the heatbegins to operate upon the contents of the innerone,” as this is simply stating that if a kettle on afire were divided in the middle so as to form twodistinct cavities or chambers, the water would boilin the one, while in the other it would be only warm.