20, 6 Mendiola: Weight and Ash Content of Tobacco 653 
TABLE 23.—Proportion of dry ‘weight and ash to 100 cubic centimeters of 
water transpired. 
Shaded. 
Water (cc.) 100. 
Dry weight (g.) 0.2735 
Ash (g.) 0.0300 
Unshaded. 
Water (cc.) 100. 
Dry weight (g.) 0.2367 
Ash (g.) ; : 0.0197 
The single fresh-weight determination made in this study 
(Table 5) showed that the “dry” plants were heavier. 
Dry matter.—Determinations of dry weight as well as of 
ash were made, not only of the entire plant, but also of roots, 
stems, and leaves separately in order to determine if the relative 
amounts of dry matter and ash vary in different parts of the 
plant. Information on this particular point ought to be of value 
in considering the merit of the data heretofore reported by dif- 
ferent investigators for only a portion of the plant. Except in 
one case, analysis was of individual plants in order that the 
probable error due to individual variation could be determined. 
Ash.—Ash is reported in the foregoing tables as percentage 
of dry weight, except in Tables 17 and 23. Since both the dry 
weight and the corresponding ‘percentage of ash are given, the 
amount of ash, if desired in other cases, can be calculated very 
easily. In the younger crop it is seen (Table 7) that the per- 
centage of ash in the roots and stems of the “humid” plants is 
greater than that in those of the “dry” ones; while in the case 
of leaves, the difference, though small, is in favor of the 
“dry” plants. As probable errors were not determined in this 
particular case, nothing can be said about whether or not the 
differences are significant. Taking the data in Table 15, which 
represent the percentages of ash in another, younger crop, the 
above comparison still holds and it is to be seen that the differ- 
ence is significant for the stems. Taking the dry weight of the 
entire plant (Table 16) of the same crop, there was more dry 
matter in the “humid” than in the “dry” plants, but a slightly 
smaller percentage of total ash. If the total amount of ash is 
calculated, it will be found that in this the two crops do not 
Be. case of the older crop in dry and humid conditions, 
i i i d leaves 
the differences in percentages of ash in roots, stems, an 
are all in favor of the humid plants (Table 10), but the reverse 
