Talbot is one of the early researchers into the field of spectral analysis. Between 1826 and 1836 he made several significant contributions and deserves recognition as one of the founders of modern spectrochemical analysis.
William Henry Fox Talbot is generally regarded as one of the founders of modern photography. Of two biographical encyclopedias of science consulted, only one contains an entry but makes no mention of any contributions to spectroscopy (1). The internet sites are scarcely better (2,3). However, some older texts on spectroscopy do note his experiments with flame spectra (4–6) and the latter two considered him the founder of spectrochemisty, a title traditionally reserved for Kirchhoff and Bunsen. One such claim might well be dismissed, but two would seem to demand further investigation.
English classical scholar, mathematician, scientist, and inventor William Henry Fox Talbot was born on February 11, 1800, in Melbury, Dorset, England. He was the son of William Davenport Talbot, an officer in the Dragoons, and Lady Elizabeth Fox Stangeways, daughter of the second Earl of Ilchester. His father died when he was but five months old. However, to his good fortune, his stepfather — his mother remarried in 1804 — treated him with love (3).Talbot entered Trinity College in Cambridge, England, in 1817 where he won prizes in Greek verse. He graduated with classical honors in 1921 and was 12th in his class in mathematics (3).
In 1826 Talbot published a paper entitled "Some Experiments on Coloured Flames." He described using an alcohol burner and simple spectroscope to observe the flames produced by salts of sodium, potassium, and strontium. Discussing the red line observed with the flame of niter or of a chlorate of potash, Talbot wrote
The red ray appears to possess a definite refrangibility and to be characteristic of the salts of potash, as the yellow ray is to the salts of soda. . . . If this should be admitted I would further suggest that whenever the prism shows a homogeneous ray of any colour to exist in a flame, this ray indicates the formation or the presence of a definite chemical compound.
In 1834, in a paper entitled "Facts Relating to Optical Science," Talbot noted that the flame spectra of strontium and lithium salts were visually indistinguishable. He wrote
The strontia flame exhibits a great number of red rays well separated from each other by dark intervals. . . . The lithia exhibits one single red ray. Hence I hesitate not to say that optical analysis can distinguish the minutest portions of these two substances from each other with as much certainty, if not more, than any other known method.
It is for this statement that Twyman (6) considers Talbot to be the discoverer of spectrochemical analysis.
In 1835 Talbot wrote on the nature of the continuous spectrum, which he correctly attributed to the heating of matter:
Later in the same paper he comments on the dark lines in the spectrum produced by iodine vapor: "I have found by careful observation that they are not equidistant, but that they become gradually more crowded towards the blue end of the spectrum. This . . . seems a consequence of some simple general law."
Still later he notes, :
The quotations above are all from Frank Twyman (6), managing director of Hilger Ltd. for many years, who was a significant player in the development of spectroscopic instrumentation in the early decades of the 20th century. Inasmuch as this author has no access to the originals, the papers quoted by Twyman are as follows: Brewster J. Sci. 5, 77 (1826); Phil. Mag. 3(4), 112–114, (1834); Phil. Mag. 3(7), 113 (1834).