Hillebrand[182] has called attention to the fact that the igneous rocks of the Rocky Mountains showed a higher percentage of barium than rock from other portions of the United States, so that under these conditions one might expect the presence of barium in plants growing in this region. A sample of _Aragallus lamberti_ and one of _Astragalus mollissimus_ were sent to the Bureau of Chemistry for spectroscopic examination for various elements and they reported traces of barium in each.[183] With these arguments the writer felt sure of the presence of barium, and the matter was discussed with Dr. E. C. Sullivan, of the United States Geological Survey, and he kindly corroborated the conclusions reached as to the presence of barium, controlling its presence by means of the spectroscope, and estimated it roughly as 0.1 per cent BaO in the ash of a sample of _Aragallus lamberti_ (6.3 milligrams BaSO_{4} in 4 grams ash). This determination was made by Hillebrand's method. Kobert has anticipated this result, saying that "all plants are in the position occasionally to take up barium combinations from the soil," and "the plants which thus contain barium may act injuriously to men and animals."[184] * * * * * FOOTNOTES: [161] Swain, R. E., and Harkins, W. D. Arsenic in Vegetation Exposed to Smelter Smoke. Journ. Amer. Chem. Soc., vol. 30, p. 915. 1908.--Harkins, W. D., and Swain, R. E. The Chronic Arsenical Poisoning of Herbivorous Animals. Journ. Amer. Chem. Soc., vol. 30, p. 928, 1908. [162] A similar extract was sent to the Bureau of Chemistry, and that Bureau also reported an absence of the elements of the H_{2}S group. [163] Bachem, C. Pharmakologisches über einige Edelerden. Arch. Internat. de Pharmacodyn., vol. 17, p. 363. 1907. [164] Sestini, F. Esper. di Vegetaz. del Frumento con Sostituz. della Glucina alla Magnesia. Staz. Sper. Agrar. Ital., vol. 20, p. 256. 1891.--Di alcuni Elementi Chimici Rari a Trovarsi nei Vegetabili. Staz. Sper. Agrar. Ital., vol. 15, p. 290. 1888. NOTE.--The ammonium sulphid precipitate was very small if the phosphates were first removed with tin and nitric acid. [165] Böhm, C. R. Darstellung d. seltenen Erden, vol. 1, p. 40. 1905. [166] Wait, C. E. Occurrence of Titanium. Journ. Amer. Chem. Soc., vol. 18, p. 402. 1896. NOTE.--There seem to be no records of any study of the pharmacological action of titanium. [167] Compare Jaksch, R. v. Ueber Mangantoxikosen und Manganophobie. Münch. Med. Woch., p. 969. 1907. [168] Wohlwill, F. Ueber d. Wirkung d. Metalle d. Nickelgruppe. Arch. f. Exper. Path., vol. 56, p. 409. 1907. [169] Laband, L. Zur Verbreitung des Zinkes im Pflanzenreiche. Zeits. f. Untersuch. d. Nahrungs u. Genussmittel, vol. 4, p. 489. 1901.