n. In about half a minute there
was a sharp concussion, and Sadler said: 'See, it is that stuff on the
steam plate.' I grabbed the whole thing and threw it in the sink, and
poured water on it. I saved a little of it and found it was a terrific
explosive. The reason why those little preliminary explosions took place
was that a little had spattered out on the edge of the filter paper,
and had dried first and exploded. Had the main body exploded there would
have been nothing left of the laboratory I was working in.

"At another time, I had a briquetting machine for briquetting iron ore.
I had a lever held down by a powerful spring, and a rod one inch in
diameter and four feet long. While I was experimenting with it, and
standing beside it, a washer broke, and that spring threw the rod right
up to the ceiling with a blast; and it came down again just within
an inch of my nose, and went clear through a two-inch plank. That was
'within an inch of your life,' as they say.

"In my experimental plant for concentrating iron ore in the northern
part of New Jersey, we had a vertical drier, a column about nine feet
square and eighty feet high. At the bottom there was a space where two
men could go through a hole; and then all the rest of the column was
filled with baffle plates. One day this drier got blocked, and the ore
would not run down. So I and the vice-president of the company, Mr.
Mallory, crowded through the manhole to see why the ore would not come
down. After we got in, the ore did come down and there were fourteen
tons of it above us. The men outside knew we were in there, and they had
a great time digging us out and getting air to us."

Such incidents brought out in narration the fact that many of the men
working with him had been less fortunate, particularly those who had
experimented with the Roentgen X-ray, whose ravages, like those of
leprosy, were responsible for the mutilation and death of at least one
expert assistant. In the early days of work on the incandescent lamp,
also, there was considerable trouble with mercury. "I had a series of
vacuum-pumps worked by mercury and used for exhausting experimental
incandescent lamps. The main pipe, which was full of mercury, was about
seven and one-half feet from the floor. Along the length of the pipe
were outlets to which thick rubber tubing was connected, each tube to a
pump. One day, while experimenting with the mercury pump, my assistant,
an awkward country lad fro