Under Secretary of State for Foreign Affairs--and had seen the
director of the government mines at Saarbruck, who gave it as his
opinion that, so far as his experience had gone, the new explosive was
a most valuable invention. Mr. Walker was so impressed with the great
advantages of roburite that he desired to introduce it into his own
colliery, where he gladly arranged with the company to make the first
coal mining experiments in this country. These were recently carried
out in the Parkgate seam of the Wharncliffe Silkstone colliery, under
the personal superintendence of the inventor, Dr. Roth, and in the
presence of a number of colliery managers and other practical men.

In all six shots were fired, five of which were for the purpose of
winning coal, while the sixth was expressly arranged as a "blowout
shot." The roburite--which resembles nothing so much as a common
yellow sugar--is packed in cartridges of about 4½ in. in length and 1½
in. in diameter, each containing about 65 grammes (one-seventh of a
pound) inclosed in a waterproof envelope. By dividing a cartridge, any
desired strength of charge can be obtained. The first shot had a
charge of 90 grammes (one-fifth of a pound) placed in a hole drilled
to a depth of about 4 ft. 6 in., and 1¾ in. in diameter. All the
safety lamps were carefully covered, so that complete darkness was
produced, but there was no visible sign of an explosion in the shape
of flame--not even a spark--only the dull, heavy report and the noise
made by the displaced coal. A large quantity of coal was brought
down, but it was considered by most of the practical men present to be
rather too much broken. The second shot was fired with a single
cartridge of 65 grammes, and this gave the same remarkable results as
regards absence of flame, and, in each case, there were no noxious
fumes perceivable, even the moment after the shot was fired. This
reduced charge gave excellent results as regards coal winning, and one