With respect to the action of cordite upon guns, Sir A. Noble points out that the erosion caused is of a totally different kind to that of black powder.  The surface of the barrel in the case of cordite appears to be washed away smoothly by the gases, and not pitted and eaten into as with black powder.  The erosion also extends over a shorter length of surface, and in small arms it is said to be no greater than in the case of black powder.  Sir A. Noble says in this connection:  “It is almost unnecessary to explain that freedom from rapid erosion is of very high importance in view of the rapid deterioration of the bores of large guns when fired with charges developing very high energies.  As might perhaps be anticipated from the higher heat of ballistite, its erosive power is slightly greater than that of cordite, while the erosive power of cordite is again slightly greater than that of brown prismatic.  Amide powder, on the other hand, possesses the peculiarity of eroding very much less than any other powder with which I have experimented, its erosive power being only one-fourth of that of the other powders enumerated.”

TABLE GIVING SOME OF SIR.  A. NOBLE’S EXPERIMENTS.
____________________________________________________________

____________
|                                                                        |
|                          VELOCITIES OBTAINED.                          |
|___________________________________________________________

_____________|
|                            |          |          |          |          |
|                            | In a 40  | In a 50  | In a 75  | In a 100 |
|                            | Cal.  Gun.| Cal.  Gun.| Cal.  Gun.| Cal.  Gun.|
|____________________________|__________|__________|________

__|__________|
|                            |          |          |          |          |
|                            |Foot Secs.|Foot Secs.|Foot Sees.|Foot Secs.|
|                            |          |          |          |          |
|With cordite 0.4 in. diam.  |   2,794  |   2,940  |   3,166  |   3,286  |
|  "     "    0.3      "     |   2,469  |   2,619  |   2,811  |   2,905  |
|  " ballistite 0.3 in. cubes|   2,416  |   2,537  |   2,713  |   2,806  |
|  " French B.N. for         |          |          |          |          |
|        6-inch guns         |   2,249  |   2,360  |   2,536  |   2,616  |
|  " prismatic amide         |   2,218  |   2,342  |   2,511  |   2,574  |
|                            |          |          |          |          |
|____________________________|__________|__________|________

__|__________|
|                                                                        |
|                  ENERGIES REPRESENTED BY ABOVE VELOCITIES.             |
|___________________________________________________________

_____________|
|                            |          |          |          |          |
|                            |Foot Tons.|Foot Tons.|Foot Tons.|Foot Tons.|