2 _ BULLETIN 600, U. S. DEPARTMENT OF AGRICULTURE. 
In Wolff’s tables, which are the only comprehensive compilation 
of ash analyses, iron and aluminum are seldom differentiated, and 
the data given for sulphur are known to be too low.’ For the mat- 
ter under consideration in this paper these tables are of no value, 
for rarer elements were not considered. 
In the present work the number of elements sought for has been 
limited by the lack of accurate methods and the improbability of 
finding certain elements. Titanium, vanadium, chromium, molyb- 
denum, barium, strontium, lithium, rubidium, and caesium have been 
determined. 
Partly for the sake of completeness, and partly because the au- 
thors wished to find out if there has been a replacement by a less 
common but similar element, the commoner elements have also been 
determined. The data obtained are by no means complete. The 
variation of the composition of varieties was ignored; the varia- 
tion of the plant at different periods of growth and the variation 
in the composition of plants grown on different types of soil are 
only meagerly covered. 
The presence of some of the rarer elements in plants has been 
previously reported. The references given below include only those 
elements for which the plants used in this work were examined. 
BARIUM. 
Hornberger? found 0.97 and 1.20 per cent BaO in two samples 
of ash from the trunks of copper beeches. He reports the results of 
earlier investigation in which the presence of barium in beech, oak, 
birch, and wheat is noted. Crawford * supposes the poisonous action 
of loco weed to be due to barium compounds. There is a compara- 
tively large amount of barium present (0.021 BaO in the dried 
plant), but Failyer* and Alsberg and Black*® have shown that many 
other plants, some of which are excellent cattle foods, contain more 
barium than the loco weed. Alsberg and Black report from 0.006 
to 0.030 per cent BaO in various dried plants. McHargue® and 
Artis and Maxwell‘ found barium in tobacco and some other plants. 
The amount reported varied from 0.010 to 0.128 per cent BaO. 
Other investigators have reported the presence of barium in plants, 
but it is not necessary to continue the reference list, since it is well 
established that barium is a common constituent of plant ash. 
1 Hart and Peterson, Wis. Agr. Expt. Sta., Research Bulletin No. 14 (1911). In most 
cases in Wolff’s tables the sulphur was determined in the ash after burning. Skinner, in 
Bulletin No. 116, Bureau of Chemistry, U. S. Dept. of Agr. (1908), has shown that 
cottonseed meal and mustard-seed meal lose $0 and 92 per cent, respectively, of their sul- 
phur when ashed. : 
2 Land. Vers-Stat., 51, 473 (1899). 
* Bul. 129, Bureau of Plant Industry, U. S. Dept. of Agr. (1908). 
4 Bul. 72, Bureau of Soils, U. S. Dept. of Agr. (1910). 
> Bul. 246, Bureau of Plant Industry, U. S. Dept. of Agr. (1912). 
¢J..Am. Chem. Soc., 35, 826 (4913). 
7Chem, News, 114, 62 (1916). 
