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).
Letter from H.M. Hobson, Ltd. discussing liquid discoloration in gauges, potential causes like water contamination, and solutions such as using Crookes glass.
| Identifier | ExFiles\Box 61\3\ scan0206 | |
| Date | 25th June 1931 | |
| Messrs.Rolls-Royce,Ltd., Date 25.6.31. Page 3 and the liquid interchanging and being mixed with the reservoir of liquid in the back tube. Further, and probably most important of all, the inclusion of even a small amount of water in the "U" tube assembly, probably during the course of manufacture, will cause a definite discoloration of the liquid. We have no means of telling at present, but it is possible that during the cleaning of the "U" tube prior to the introduction of the liquid, a small amount of water might have remained in the tubes. This will of course in time set up discoloration, but we do not think it quite certain that it would be cause of definite fading. We believe that the steps which we are now taking will for all practical purposes eliminate the fading trouble in your standard gauges as used on your cars. As far as we are able to judge, the only disadvantage of using Crookes glass, which undoubtedly retards the action of the ultra-violet rays upon the colour of the liquid, is a slight lack of transparency as compared with ordinary glass. We remain, dear Sirs, Yours faithfully, H.M.HOBSON,Ltd., [Signature] Joint Managing Director. | ||