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).
Spark test report on the carbonization of Elo and Bakelite materials compared to ebonite.
| Identifier | WestWitteringFiles\G\August1921\ Scan31 | |
| Date | 4th August 1921 | |
| EFC. AB.15 4th Aug. 1921. X.3513 - SPARK TEST OF ELO AND BAKELITE. The piece of Elo received from Mr. Bailey under By5/P7.7.21 has now been tested for carbonization due to surface sparking. A very severe spark was first tried, by using an R.{Sir Henry Royce} Bosch magneto with a small single mica plate condenser across the gap, the spark being passed across the edge of the sample which is just 10mm. wide. A few minutes of this caused a carbon track to form through which the current from the magneto then passed quietly instead of discharging through the air. This path conducted sufficiently to light a lamp on 200 volts though it became red hot and smoked with the current. A similar experiment was carried out with a small piece of bakelite and exactly similar results were obtained. A piece of ebonite subjected to the same treatment merely burned away without forming a conducting path. The Elo was now subjected to sparking from the R.R. std. battery ignition. This was continued for 65 hours (using one out of 6 sparks as was done with the magneto) at the end of which time fairly deep grooves had formed along the path of the spark, but which in no way became conducting. These tests confirm that bakelite products are not a good substitute for ebonite for withstanding sparking though it requires a good deal of sparking to produce any serious effect. FJA. R'R' 3327 (1000.L) | ||