The Ingenious Alfred Walker Empson
In the Public Record Office at Kew a small Admiralty File is located at ADM 227/182. This contains a report produced In February 1938 for the Admiralty Engineering Laboratory at West Drayton by J. H. Darley A.I.C. The report entitled "Purification of Dirty Lubricating Oil by the Stone-Empson Coagulator", is very detailed description of tests made of this equipment, presumably to assess its suitability for use by the Admiralty.
"It is claimed for the Stone-Empson Oil Purifting Unit that it will remove impurities continuously, particularly colloidial carbon, from oil more effectively than can be done by centrifuging only. The experiment was carried out to investigate the validity of this claim."
The report does just that, taking seven typed pages to do so. It contains reproductions of photomicrographs made of samples of oil during the testing process, a photograph of the mechanism and a detailed diagram of the system used in the test, the latter two of which which are reproduced below.
The report initially appears to conclude that the process of coagulation which lies at the heart of the invention, is not particularly effective at cleaning oil in comparison with other methods. However Alfred Empson appears to have been consulted over the findings and made important observations 'criticisms' of the methods used.
The Admiralty scientists then examined an 'Empson Oil Purification Unit' at work at the Brixton Pumping Station of the Metropolitan Water Board. That unit had by then been in use for some 4 1/2 years and was considered to be effective. Taken together the results of the two elements of the examination suggest that the machine was effective. It 'lengthened the useful life of oil which was regularly cleaned by means of the device' and 'enabled impurities to be filtered out of dirty oil'. The report concludes however that "Neither in the experiments carried out at the A.E.L. nor in the tests made on an Empson unit at Brixton did the quality of the purified oil approach that of unused pure oil."
I have not reproduced the whole report here but would be willing to send further details to anybody who is particularly interested.
A Curious Coincidence
Finally, in one of those happy coincidences that seem to be a feature of family history research, Kenneth Empson (my father) tells me that he once worked with J. H. Darley at the Admiralty. When Dad left Plymouth Dockyards to work as a Draughtsman, Darley was for a time his boss and became something of a mentor. He says that the report is typical of Darley's work, meticulous and precise. The man himself was always impeccably dressed and placed much store on manners and 'proper' behaviour. He remembers being told by Darley that no matter how old or worn his clothing might be, he should always strive to carry it in a good quality suit-case, and claims that he has followed this advice ever since!
The Stone-Empson Purifier
(It is assumed that this picture is of the equipment as set up at Brixton.)
Diagram showing the equipment set up for the Admiralty tests.
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