The Romance of Modern Chemistry

INVISIBLE SUBSTANCES affected by this poisonous gas more rapidly than human beings, and the behaviour of mice therefore serves to give warning of its presence in dangerous proportions. After the Snaefell Mine disaster in 1897, for instance, the rescue party, headed by Professor Le Neve Foster, descended ladder after ladder in the shaft only after a mouse had been previously let down to the next lower level. A lighted candle also was attached to the cage containing the mouse. “ By the aid of this testing apparatus,-” says Professor Foster in his Report, “ it was easily ascertained without any risk that the air was not bad as far as the 115 fathoms level, and that it became poisonous and deadly at the 130. The mice showed precisely the same symptoms as human beings; for, if not completely dead on arriving at the surface, they had lost all power in their legs, whilst pinkness in the snout recalled the pink lips of the dead bodies of the unfortunate miners.” Until recently it was the regular custom to carry a couple of white mice on every submarine boat, the object being the detection of any carbon monoxide which might be produced by imperfect combustion of the gasolene. It appears, however, that mice are not sufficiently sensitive to small quantities of the gas, and the practice of carry- ing them on submarines is now quite rare. The question may have occurred to the reader— how does it come about that gases, while obeying the fundamental laws of matter in many respects, are yet so utterly different from the more compact forms of matter with which we are acquainted—namely, liquids and solids ? It is not only that gases are frequently invisible, but they are peculiar also in their ability to occupy fully any space that is offered to them. If a quantity of gas which fills a ten-gallon gasometer is