nature of the soil upon which the cotton is grown. The tubes of the fibre
seem to be open at one end only when the fibre is of normal length. When,
therefore, the cotton is subjected to the action of the mixed acids, the
line of least resistance seems to be taken by them, viz., the insides of
the tubes constituting the fibre of the cotton, into which they are taken
by capillary attraction, and are subject to change as they progress, and
to the increased resistance from the oil or gum, &c., in their progress,
and therefore to modified action, the result of which is slower and slower
action, or chemical change. He also thinks it is possible that the power
of capillary attraction is balanced in the tubes by air contained therein,
after a little, sufficiently so to prevent the acids from taking full
effect. To get over this, Mr France uses his cotton in a fine state,
almost dust, in fact, and then nitrates in the usual mixture of acids at
40° to 90° F., the excess of acids being removed by pressure. He says he
does not find it necessary to wash this fine cotton dust in an alkaline
solution previous to nitration. His mixed acids consist of 8 parts HNO_{3}
= 42° B., and 12 parts H_{2}SO_{4} = 66° B., and he stirs in the dipping
tank for fifteen minutes, the temperature being 50° F. to 100° F., the
temperature preferred being 75° F.

~"Nitrated" Gun-Cotton.~--The nitrates that are or have been mixed with
gun-cotton in order to supply oxygen are potassium nitrate, ammonium
nitrate, and barium nitrate (tonite). The total combustion of gun-cotton
by potassium nitrate corresponds to the equation:--

10[C_{24}H_{18}(NO_{3}H)_{11}O_{9}] + 82KNO_{3} = 199CO_{2} +
41K_{2}CO_{3} + 145H_{2}O + 96N_{2},

or 828 grms. of nitrate for 1,143 grms. of gun-cotton, or 42 per cent.
nitrate and 58 per cent. gun-cotton. The explosive made at Faversham by