From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Experiment investigating the effects of sparking on tungsten points.
| Identifier | ExFiles\Box 35\6\ scan 050 | |
| Date | 1st June 1921 guessed | |
| -2- Con d An hour or two of this sufficed to form a deep purple scale on the surfaces, while the surrounding area was covered with a white deposit. The run was continued for 45 hours, but without much further change, no metal or oxide being transferred as there was no preponderance of current in either direction. It thus seems to be demonstrated that our difficulties with tungsten points are not due to current density, but that when a spark occurs, the oscillatory portion (which is doubtless of very high temperature) damages the surface of the metal, while the uni-directional portion transfers the metal from one point to the other. The necessity for eliminating sparking as suggested in the above mentioned note is thus confirmed. F.J.A. | ||