Part 17 (1/2)

Pyrocollodion: highly nitrated, soluble gun-cotton. Adopted by the United States.

White Gunpowder: a mixture of pota.s.sium chlorate, pota.s.sium ferrocyanide, and sugar. Very sensitve, and only used in the laboratory.

PROPELLANTS FOR SHOT-GUNS

Amberite: insoluble nitrocotton 18.6 per cent, nitrates 28 per cent, soluble nitrocotton 46 per cent, vaseline 6 per cent.

Du Pont Smokeless Powder: nitroglycerine 10 per cent, ammonium nitrate 67.5 per cent, wood-pulp 8 per cent, salt 15 per cent (for coal-mines).

Soluble nitrocotton 46 per cent, metallic nitrates 2.2 per cent (for shot-guns).

E.C. Powder: insoluble nitrocotton 44 per cent to 48 per cent (Empire Powder), soluble nitrocotton 30 per cent to 34 per cent, metallic nitrates 14 per cent to 9 per cent, vaseline 6 per cent to 7 per cent, camphor 4.6 per cent.

Ideal Powder: made by n.o.bels.

Neonite. Similar to the above compositions, but containing 73 per cent of insoluble nitrocotton, 9 per cent soluble nitrocotton. It is also made for rifled small-arms especially for rim-fire rifles.

New Explosives Company Smokeless Powder. Similar to above.

Rifleite: insoluble nitrocotton 1.7 per cent, soluble nitrocotton 82.5 per cent, nitro-body 4.8 per cent. The nitrocellulose is made from curc.u.ma.

Ruby Powder: a cheap non-solvent powder, 46 per cent insoluble nitrocotton, 4 per cent soluble nitrocotton.

Smokeless Diamond and Stoumarkel Smokeless are similar to above.

PROPELLANTS FOR RIFLED FIRE-ARMS

Amide Powder: ammonium nitrate, pota.s.sium nitrate, charcoal. Has also been used in German artillery.

Ammonpulver: ammonium nitrate and charcoal. Has been used by Austrian artillery, and lately reintroduced by the Germans.

Ballist.i.te: equal parts of nitroglycerine and soluble nitrocotton with some mineral jelly.

Cordite: the princ.i.p.al smokeless powder of the British Empire.

Indurite: gun-cotton and nitrobenzene. Abandoned by U.S. navy.

Neonite: a gelatinized powder. Contains nitrocellulose insoluble and soluble, metallic nitrates, and vaseline.

Noddite: a strip sporting-rifle powder containing nitroglycerine, nitrocellulose, mineral jelly.

Rottweil Smokeless Powder: a gelatined powder containing camphor and diphenylamine.

See also _Grenade_; _Sh.e.l.l_; _Torpedo_; _Fireworks_; _Rockets_.

EXPO'NENT. In algebra a^3 denotes three a's multiplied together; a^n means that n of the letter a are to be multiplied. These numbers or letters placed immediately above and to the right of another number or letter are called exponents, and indicate the power to which the number or letter is raised. Exponents can be fractional or negative, in which case new interpretations can be found. On the a.s.sumption that a^m a^n = a^{m+n} for all values of m and n, a^{1/n} is interpreted as the nth root of a, a^{-n} as the reciprocal of a^n.

EXPONENTIAL THEOREM. If a^x = N, x is said to be the logarithm of N to the base a. There are two bases of logarithms in common use, the base 10 and the Napierian base e. The exponential theorem states that the value of e^x is given by the infinite series 1 + x + x^2/(1.2) + x^3/(1.2.3) + ... + x^n/(1.2.3..n) +, &c. Putting x equal to 1, e = 1 + 1 + 1/(1.2) + 1/(1.2.3) + 1/(1.2.3.4) +, &c. e can be expressed to any number of decimal places by working out the value of the terms on the right-hand side. It is an incommensurable number which to five decimal places is equal to 2.71828.

See _Logarithm_.

EXPORTS. See _Foreign Trade_.

EX POST FACTO, in law, a term designating something as done after and bearing upon something previously done; thus a law is said to be _ex post facto_, or retrospective, when it is enacted to punish an offence committed before the pa.s.sing of the law.