Sir William Crookes was one of the scientific giants of the Victorian and Edwardian ages. His chemical investigations ranged across many fields, and one of the last immortalised his name in optics. His personal life, however, was somewhat complicated; not least because of his researches into spiritualism and his questionable relationship with a young medium.
Crookes (1832–1919) was in the fortunate position of inheriting a great deal of money from his father, allowing him to set up his own private laboratory in Notting Hill, London. He had studied at the Royal College of Chemistry and, after short spells as superintendent of the meteorological department of Oxford’s Radcliffe Observatory and working at the College of Science in Chester, he continued to pursue his various investigations at his London base. He was a rarity for such a prominent scientist in that, other than these two brief sojourns, he never held an academic position; this, and his argumentative nature, may account for the fact that he only once published a scientific paper jointly with another named person.
His first major contribution to science was his discovery of thallium in 1861, making him the first Englishman to discover an element since Sir Humphry Davy’s isolation of boron in 1808. Precedence for the discovery of thallium was a hard-fought affair against the claims of a Frenchman, Claude-Auguste Lamy, with international recognition only coming when a Swedish mineralogist identified a rare thallium-containing mineral and named it crookesite.
[CaptionComponent="1901"]Perhaps even more significant were Crookes’ experiments on cathode rays. Developing an earlier piece of apparatus, he invented a glass tube in which a near-vacuum could be created and across which a high electrical voltage could be applied, from a cathode at one end to an anode near the other end. As the gas pressure was reduced inside the tube, the stream of cathode rays would hit the end of the tube causing it to fluoresce yellowish-green.
Crookes maintained that the rays travelled in straight lines; to prove this he introduced the familiar Maltese cross-shaped target into the path of the rays, which resulted in the formation of an identically shaped shadow on the end of the tube.
In 1897, JJ Thompson identified cathode rays as electrons, the first subatomic particles to be found. The Crookes tube was also crucial to Wilhelm Röntgen’s discovery of X-rays in 1895, a fact acknowledged in a contemporary Scientific American article.
[CaptionComponent="1902"]By now Crookes was becoming part of the scientific and social establishment. It helped that he had George Stokes as a patron, another famous name in optical theory, who, among other things, facilitated Crookes’ election to membership of the influential Athenaeum Club. He was also admitted to the Freedom and Livery of the Worshipful Company of Spectacle Makers in 1899, an organisation that, at the time, was more concerned with attracting the great and the good of the City than with its optical heritage. At different times he was elected president of both the British Association for the Advancement of Science (BAAS) and the Royal Society.
As a public figure, Crookes became involved in several pressing issues of the day, such as water quality, sewage, hygiene and public health; agriculture and the fixation of nitrogen from the atmosphere (his own experiment predicted production on an industrial scale, later realised in the Haber-Bosch process); the commercial production of Welsh gold; and electric lighting. The latter subject was a matter of feverish research: could electric lighting become an economic replacement for gas lighting? Edison in the US and Swan in England patented electric incandescent light bulbs, but so did Crookes. He also installed electric lighting in his own house, an experiment he recounted in a letter to The Times (June 5, 1882) and entered the debate on electrifying the Athenaeum’s lighting.
Crookes’ research on ophthalmic tints was to be one of his last contributions to public and occupational health. But even in his eminence, he was still occasionally dogged by a scandal from many years previously. Initially a sceptic of the new craze of spiritualism that was sweeping the country, Crookes attended a séance after his younger brother, Philip, had died at sea.
Philip appeared to speak through the medium with convincing detail (although much information had been made public during a libel trial between Crookes and the ship’s captain) and Crookes was hooked. He read voraciously on spiritualism and was introduced to another medium, 17-year-old Florence Cook.
Crookes was not alone in investigating these new psychic phenomena from a scientific viewpoint. But his papers in scientific journals that proposed a psychic force left him open to ridicule. Thereafter, he wrote up his research for the spiritualist audience. His initial investigations had been into a medium called Daniel Home, but his dalliance with the pretty Florence Cook led some to ask just how close his association with her was.
Despite what he thought were foolproof electrical experiments (the medium was wired up to a galvanometer to detect any supposed unwarranted movement from their concealed seat), Crookes was duped by two other mediums – Rosina Showers, a friend of Cook, and an American, Annie Fay. Scandal broke when the first two were eventually unmasked as frauds, while Fay was a known professional illusionist.
Although Crookes disagreed, the physicist William Barrett, reading a paper at a subsequent BAAS meeting, was surely correct in saying, ‘a trained physical inquirer is no match for a professional conjurer’.
In 1908, due to government concerns about eye injuries from glare, the Royal Society set up a Glass Workers Cataract Committee. Crookes, now in his 80s, experimented with how various metal oxides added to glass might reflect infrared from white-hot furnaces, and photographed spectra of molten glass. He told the committee that ‘it should be possible to make a glass that would be opaque to the infrared and ultraviolet... but, hitherto, I have been unsuccessful’.
Only in 1913 did he find a solution that was opaque to ultraviolet and accounted for 90 per cent of infrared, while being only lightly tinted. He realised, though, that protective tinted lenses would be useful for leisure purposes too, so tested more than 300 formulations, each numbered and labelled. For example, Crookes Glass 246 was the tint recommended for glassworkers. A light sage-green colour, containing ferrous oxalate with some red tartar and wood charcoal, it eliminated 98 per cent of incident heat.
The best-known Crookes tints are the A, A1, B and B2 series, all of which absorb all ultraviolet radiation below 350nm while reducing luminosity of the visual spectrum. Crookes’ samples were produced at the Whitefriars glassworks in London, specialists in stained glass, and Chance Brothers, Birmingham. An accident occurred at the latter when a batch of Crookes A glass became contaminated with blue cullet (scraps of waste glass), resulting in a pleasant blue tint. Patented in 1926 as Crookes A2, it became very popular in spectacles.
Crookes B and B2 were medium and dark shades of greenish smoke. Of course, the Crookes Alpha tint (very pale blue) is well-known; it replaced the very pale green Crookes A that was withdrawn for safety reasons due to its uranium content.
Sir William Crookes was a remarkable example of the Victorian gentleman scientist, able to turn his hand to almost any area of research that piqued his interest. His favourite saying was, ‘a man should always have a little more to do than he could possibly accomplish’. Crookes always had more to do, but he certainly accomplished much. A sunny day serves well as his epitaph, since sunglasses were his idea.
David Baker is an independent optometrist
