The obituary for Jack Norman Gregory (1920–80), written by Dal Swaine and published in Chemistry in Australia, omitted the most interesting of the projects that he worked on. Gregory completed his BSc at the University of Melbourne, studying part time while working with the CSIR Division of Forest Products. During World War II, he was with CSIR’s Lubricants and Bearings Section, working on lubricants and related materials under the general direction of Philip Bowden. In the late 1940s, Gregory was awarded the MSc degree for a collection of reports and publications arising from his CSIR work. Later, he moved to the Australian Atomic Energy Commission where he became Deputy Director of Research. His DSc was awarded by the University of Melbourne in 1954, again for a collection of work. The breadth of his interests and achievements stamped him as jack-of-all-trades chemist.
What I was most interested to learn about, however, was a wartime project on the production of a local version of napalm, a military weapon that was compounded from a flammable liquid such as petrol or diesel and a gelling agent. Products of this type could be used in bombs and other incendiary devices, but the best-known application was in flamethrowers that could squirt a burning mixture up to 100 metres. Because the gelling slowed down combustion, the product was still burning when it reached its target and continued to do so for some time. Napalm came in several varieties. The one we know best was based on polystyrene as gelling agent: it was very sticky when it reached its target, and very hard to extinguish. This variety was said to have been invented by Louis Fieser, Professor of Chemistry at Harvard University.
Following a request from the Australian Army in 1944, Gregory led a small team to produce a local version of this fearsome weapon. One of his colleagues was a Dutch naval officer, presumably displaced from the East Indies (Indonesia) by the advance of Japanese forces. Examination of a sample of napalm provided by the US military showed that it contained an aluminium soap. Metallic soaps were familiar to the CSIR researchers: they render lubricating oils more or less solid so they can adhere to bearing surfaces. Sodium, potassium, calcium and strontium soaps (salts of long-chain fatty acids) are in common use, as I recall from my studies at Footscray Tech all those years ago, where one of the exercises was to determine, by flame colour, what metal was involved in each of a number of grease samples.
The Australian product, Gelatrol, was prepared from an aqueous solution of alum and oleic acid, by the addition of caustic soda to produce a granular precipitate. It had the overall formula Al(OH)1.3(C17H33COO)1.7, representing a mixture of aluminium monohydroxy dioleate and dihydroxy mono-oleate. In the field, the gelling agent was mixed at a level of about 5% with motor transport fuel to produce a stable gel in a few minutes. The development of Geletrol is described in a series of CSIR reports marked ‘SECRET’, but by the time that Gregory’s collected papers were submitted for the MSc the main lines of the work had been published in 1946 in the Journal of the Council for Scientific and Industrial Research. Something revealed in one of the later reports was the improved gelation by incorporation of a small quantity of ethyl cellosolve (2-ethoxy ethanol). A touch of β-naphthol was added, too, as an anti-oxidant. Batches of a modified version of Geletrol were made by CSIR’s Chemical Engineering Section. Their gelling agent was an aluminium alkoxide, and counterintuitively it was the ethoxide that out-performed longer-chain alkoxides. Designed for ‘blaze bombs’ to be used by the Royal Navy, it was tested in bombs dropped by a Mustang aircraft at Laverton, south-west of Melbourne, where there was a military airfield.
Commercially, however, several tons of Geletrol were manufactured each week by Australian chemical companies Fletcher Chemical in Melbourne and Robert Corbet Pty Ltd in Sydney, and the army used large quantities of it in the closing stages of the war.
‘Great balls of fire’ was the exclamation I heard in the early 1960s from others who were excited about happenings in their daily life, but I’d never wondered about the origin of the phrase until it jumped into my mind when I was composing this Letter. Turns out it was the title of popular song from late 1957, sung by Jerry Lee Lewis, and the opening lyrics are a pretty good description of the flamethrower: ‘You shake my nerves and you rattle my soul’.
Readers can find a great photo of long-range flame throwing on the Digger History website (bit.ly/2MPJwb2) or the Australian War Memorial website.