Show erosion of heavy guns A serious trouble that confronts the modern artillerist is the tendency ot the smokeless powders that are now exclusively used to burn out the in gerior lining of the gun particularly near the powder chamber the pow der itself is the cause ot more or less anxiety because ot its chemical instability the erosion or burning out of the interior tube of the gun which Is in immediate contact with the powder gases is due to the high pressure and intense heat of the gases at the instant a charge is fired a great volume of gas is generated and being confined in the powder chamber by the projectile its pres sure rises to an enormous amount which in the case of the sen ice charges in the united states guns Is as high as seventeen tons to the square inch this is accompanied by a proportionate rise in the tern pera ture of the gases if it were possible to look into the powder chamber at the instant of dis charge it would be found to be daz aling white heat As the projectile begins to move down the bore of the gun these white hot gases rush out of the powder chamber and they stream from the larger chamber into the smaller bore they literally melt the hardened haid ened steel surface of the bore the process being probably as aisted by some chemical reaction not yet thoroughly understood the gases under the enormous pressure quickly find out the very smallest way of escape past the base of the shell and they stream at an enormous velocity and still at a white heat through any such slight opening and melt the hard steel of the guns just as a stream of steam or hot water would cut its ay through a block of ice british artillerists have had great trouble from erosion because of the quality of loader which they use the powder is known as cordite and the erosion is the price which the british pay tor certain desirable qualities which are absent from other powders that do not cause so much erosion cordite consists of fifty eight parts of nitroglycerin thirty seven parts of guncotton and five parta vaseline and it is the large amount of nitroglycerin that Is responsible for the serious eroding effects bulk for bulk the english powder Is much more powerful than the united states navy powder |