Collier dynamite No. 5 | Do.
Masurite M. L. F. | Masurite Explosive Co., Sharon, Pa.
Meteor dynamite | E. I. Du Pont de Nemours Powder Co.,
| Wilmington, Del.
Monobel | Do.
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“Subject to the conditions named below, a permissible explosive is
defined as an explosive which has passed gas and dust gallery tests
Nos. 1, 2, and 3 as described above, and of which in test No. 4 1½
pounds (680 grams) of the explosive has been fired into the mixture
there described without causing an ignition.

“_Provided:_

“1. That the explosive is in all respects similar to the sample
submitted by the manufacturer for test.

“2. That double-strength detonators are used of not less strength than
1 gram charge consisting by weight of 90 parts of mercury fulminate
and 10 parts of potassium chlorate (or its equivalent), except for the
explosive ‘Masurite M. L. F.’ for which the detonator shall be of not
less strength than 1½ grams charge.

“3. That the explosive, if in a frozen condition, shall be thoroughly
thawed in a safe and suitable manner before use.

“4. That the amount used in practice does not exceed 1½ pounds (680
grams) properly tamped.