THE RARER ELEMENTS IN SOILS AND PLANTS. 3 
CAESIUM. 
Von Lippmann? found caesium in the ash of the sugar beet. 
CHROMIUM. 
The ash of the Scotch fir, silver fir, some vines, poplar, and horn- 
beam was found by Demarcay? to contain spectroscopic traces of 
chromium. Jorissen* found chromium in a sample of coal from 
Liege. While this may have been originally in plant remains, there 
is doubt about it, for the same author found chromium in the shales 
im which the coal was interbedded. 
LITHIUM. 
Gaunersdorfer * studied the poisoning of plants by lithium salts 
and found that lithium is a fairly constant but not an essential con- 
stituent of some plants. 
Tschermak* found spectroscopic amounts of lithium in a large 
number of plants, though in some kinds it did not appear to be pres- 
ent. It appeared more strongly in the leaves and small stems. 
Voelker ® found that an application of 200 pounds of Li,O to the 
acre was more beneficial than potash fertilization. Contrary to this 
experience, Ravenna and Zamorani‘ found lithium salts injurious to 
tobacco and poisonous to beans and oats. 
MOLYBDENUM. 
Demareay * reports spectroscopic amounts of molybdenum in vines, 
fir, oak, hornbeam, and poplar. Jorissen® detected it in coal from 
Liege. 
RUBIDIUM. 
Pfeiffer ° found 1.75 grams rubidium chloride per kilogram of ash 
from sugar beets. This element was also found in tobacco by the 
same author. Loew *° states that small amounts of rubidium chloride 
gave increased yields of Chinese cabbage, barley, and spinach. 
STRONTIUM. 
Haselhoff * states that strontium is taken up by plants and appears 
to replace calcium when there is an insufficient supply of that ele- 
ment. In water-culture experiments larger amounts of strontium 
salts are poisonous. 
1 Ber., 21, 3492 (1888). 
2Compt. Rend., 130, 91 (1900). 
® Bul. Sci. Acad. Roy. Belg., 178 (1905). 
4Landw. Vers.—Stat., 34, 171 (1887). 
®* Zeit. Landw. Versuchsw., 2, 560 (1899). 
6J. Roy. Agr. Soc., 65, 306 (1904). 
7 Atti. Accad. Lincei. (5), 2, 626 (1909). 
8 Loc. cit. 
2 Arch. Pharm. (2); 150, 97. 
10 Bul. Col. Agr. Tokyo, Imp. Univ., 5, 461 (1903). 
1 Landw. Jahrb., 22, 851 (1898). 
