“The above partial list includes the permissible explosives that have
passed these tests prior to May 15, 1909. The announcement of the
passing of like tests by other explosives will be made public
immediately after the completion of the tests for such explosives.

“A description of the method followed in making these and the many
additional tests to which each explosive is subjected, together with
the full data obtained in each case, will be published by the Survey
at an early date.

“NOTES AND SUGGESTIONS.

“It may be wise to point out in this connection certain differences
between the permissible explosives as a class and the black powders
now so generally used in coal mining, as follows:

“(_a_) With equal quantities of each, the flame of the black powder is
more than three times as long and has a duration three thousand to
more than four thousand times that of one of the permissible
explosives, also the rate of explosion is slower.

“(_b_) The permissible explosives are one and one-fourth to one and
three-fourths times as strong and are said, if properly used, to do
twice the work of black powder in bringing down coal; hence only half
the quantity need be used.

“(_c_) With 1 pound of a permissible explosive or 2 pounds of black
powder, the quantity of noxious gases given off from a shot averages
approximately the same, the quantity from the black powder being less
than from some of the permissible explosives and slightly greater than