Page:McClure's Magazine v9 n3 to v10 no2.djvu/103

Rh idly, too rapidly for "drowning," the man would pall the valve, give a warning shout, and run. So would everybody, you included. You might run on one side to the protecting arms of a dynamite magazine holding twenty tons, or on the other to the soothing shelter of a house where gun-cotton is baking at 120 degrees Fahrenheit. Failing these, there is the pond. This is a sweet, placid pond which is formally blown up once a week because some dregs of nitroglycerin have drained into it and collected at the bottom, making it unsafe. It is comforting to feel, in the hour of danger, that you have havens of perfect security such as these.

The glycerin having duly become nitroglycerin, you flop down the stairs to another department, to witness its separation from the acids with which it is now mixed. It comes shooting down a lead gutter, and falls, a cream-colored stream, to the bottom of a lead tank, eight feet in length and two in width. As soon as the tank is full, the nitroglycerin, lighter than the acid, rises to the surface like oil. It is skimmed off in an aluminium skimmer resembling a tin wash-hand basin with a handle, and is poured into a lead pocket at the end, whence it flows through pipes to a tank, where it receives its first washing with cold water. Thence it goes through gutters farther down to another department, where it is washed with warm water and carbonate of soda. Every particle of the free acid must be removed, as remnants of it might cause chemical action, heat, and explosion in the dynamite or blasting gelatin later on. A sample is taken of each lot of nitroglycerin when made. This is placed in a small clear glass bottle and covered with blue litmus solution, to detect the presence of any remaining free acid, which would color the litmus red. En passant, your guide mentions that some years ago one of the foremen was carrying a little felt-lined box of these samples to one of the sample magazines when he unfortunately stumbled and fell. He was blown to pieces.

You have now reached the bottom of the "hill" (all nitroglycerin factories are called "hills"), and are in a wooden cabin, with a floor of loose sand, where the making of dynamite and blasting gelatin actually begins. Dynamite consists merely of liquid nitroglycerin which has been absorbed by some porous material. The liquid was discovered by Sobrero, an Italian, in 1846. Its transport and use were attended with such danger, however, that the late Alfred Nobel conceived, in 1867, the plan of absorbing it in some non-explosive medium. After experimenting with saw-dust, brick-dust, charcoal, paper, rags, and kieselguhr, he finally settled upon the last named as the best material. Kieselguhr, known in the factory as "guhr," is a silicious earth, mainly composed of the skeletons of mosses and microscopic diatoms, which is found as a slaty black peat in Scotland, Germany, and Italy. Before being used it goes to the "guhr-mill," where it is calcined in a large kiln, rolled, and sifted, the result being a very light pink powder of the consistency of flour. In the house you have entered, twenty-five pounds of kieselguhr, with about one pound of carbonate of ammonia, are weighed into a wooden box about three feet square and eighteen inches deep. Upon it is drawn seventy-five pounds of nitroglycerin from the filter tank by a man in scarlet. Another man in scarlet, with his arms bare to the shoulders, takes the box to a table, and gives it a preliminary mix, to see that all the nitroglycerin is roughly absorbed. Then a man in blue seizes it, places it with other boxes on his hand-car or "bogie," and