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 discussing investigations into fading liquid in gauges and changes to its chemical composition.
| Identifier | ExFiles\Box 61\3\ scan0186 | |
| Date | 21th May 1931 | |
| Messrs.Rolls-Royce,Ltd., Date 21.5.31. Page 2 short period we may obtain results equal to years of exposure to sunlight. In the absence of any information from King-Seeley to the contrary, we know of no time when they changed their dyeing method in connection with the liquid, and that is what makes it so inexplicable to us at the time of writing. We do know, however, of one small change which has been made in the mixture of the liquid itself during the past two years. A small amount of bromoform has been added to the acetylene tetrabromide to further reduce the freezing point of the liquid. This was found necessary for industrial gauges and on motor cars left in the open at 30 to 40 degrees of frost, which is possible under American conditions, owing to the almost universal use of anti-freezing water mixtures. We are persisting in our investigations and enquiries, and feel sure that we shall arrive at a solution of the problem, which as you rightly point out, did not occur previously. We ourselves have large quantities of gauges which have been in use for several years, and our fading troubles have been almost negligible, except in the case of the violet liquid which we mentioned to you as being in use some two or three years ago. | ||