archive.org — 2026-10-04
Queries: Google "Schuster and Hemsalech for individual spectral lines"; Hemsalech "Recherches expérimentales sur les spectres d'étincelles" thèse 1901 gallica OR archive.org; "Further experiments on the constitution of the electric spark". Full texts read from the djvu text layer (fetched to scratch, not saved to research/files).
1. G. F. Hull (Dartmouth College), "An Investigation of the Influence of Electric Fields on Spectral Lines: Preliminary Note", Proc. R. Soc. A 78 (1906), pp. 80-81 (received and read 28 June 1906; work at the Cavendish)
[web] https://archive.org/stream/proceedingsroya02britgoog/proceedingsroya02britgoog_djvu.txt (vol. lxxviii A). Item (3): with Cd/Hg amalgam electrodes in air, viewing along the discharge vs at right angles, "no variation of the wave-lengths of the strong Cd, Hg, lines greater than 0.002 tenth-metres" (echelon spectroscope). Hull's conclusion: "the luminous particles do not acquire a velocity in the direction of the discharge greater than 150 metres per second. Hence the curving of the image of the discharge produced by a rotating mirror, as in the Feddersen experiment, and as recently studied by Schuster and Hemsalech for individual spectral lines, appears to be due not so much to motion of luminous particles as to the propagation along those particles of a condition of luminosity." Bearing: a direct Doppler test of claims 1, 2 and 4 (vapour moving at ~400-1500 m/s). Evidence against the moving-vapour reading of the line slope, stated by Hull as a preliminary note. Points for reviewers: Hull's discharge conditions (capacity, gap, "small capacity inserted") differ from Schuster-Hemsalech's six-jar spark; a Doppler shift averages over particles moving toward and away from each pole (vapour streams from both electrodes in opposite directions), which could broaden rather than shift lines. Not verified here; flagged for the physicist.
2. Gustave A. Hemsalech, "Recherches expérimentales sur les spectres d'étincelles", Paris: A. Hermann, 1901 (thesis; dedicated to Schuster)
[web] https://archive.org/details/recherchesexpri01hemsgoog (also https://archive.org/details/IA41555416_0051). - Introduction: the research is "basées sur la découverte faite par M. Schuster et moi" that increasing the self-induction of the condenser discharge circuit transforms the spark spectrum; Thalén had used an iron-cored coil earlier, but "le noyau de fer détruit les oscillations". Disputes Berndt's contrary ultraviolet results (Berndt's self-induction max 0.0064 H, "beaucoup trop faibles"; cylindrical projection lens unsuitable). - Pp. 4-7: retells the 1899 work with the full paper's citation "Phil. Trans., t. CLXXXXIII, pp. 189-213"; steel disc 33 cm, second disc 22 cm, circular film 30 cm diameter; ~120 turns/s, ~100 m/s. Without prism the initial discharge ("trait lumineux") is a straight line, then curved bands (oscillations) in the "auréole"; with prism, straight lines = air, curved = metal; successive repetition of metal lines (bismuth, mercury) follows the oscillations. Model: initial discharge through air → air made incandescent → gap fills with metal vapour carried by initial discharge (auréole) → oscillations pass through and heat the vapour. - With coreless self-induction the "trait lumineux" weakens until the spark "semble formée uniquement de la vapeur métallique incandescente" (sphere or ellipsoid shape). - Conclusions (pp. 127-131): 14 metals fall in two groups: iron group (Fe, Mn, Co, Ni) whose lines are strengthened by self-induction (spark becomes arc-like; vapour forms a "pont conducteur"), and Cd, Zn, Mg, Al, Sb, Sn, Bi, Pb, Cu, Ag whose lines weaken. Proposes three temperature regions in a spark (initial discharge line, hottest; vapour with rapid oscillations; the auréole proper) and that the spark-vapour temperature "ne peut dépasser de beaucoup la température de l'arc électrique". Bearing: the inventor's own later work extending claim 3 (air first, then metal vapour carries the oscillations) and the self-induction experiment; bears on claim 4's temperature estimate (2700 K for Cd).
3. T. Royds, "XXVII. Further experiments on the constitution of the electric spark", Phil. Mag. (6) 19 (1910) 285-290 [web] archive.org crossref-pre-1923 item (Google listing) and HathiTrust Kayser Handbuch der Spectroscopie v.6 citation. Opening (snippet): "The results, obtained by photographing on a rapidly moving film the spectrum of an oscillatory spark, in the manner first employed by Schuster and..." Not opened (time).
4. Also listed (not opened): "An Introduction to the Study of Spectrum Analysis" (archive.org PDF) snippet: "Schuster and Hemsalech have observed that in the electric discharge the elements of small atomic weight, such as magnesium and aluminium, are projected from ..." [web, Google snippet].
Result: positive. Recheck: yes.