250 BULLETIN OF THE BUSSEY INSTITUTION. 
From hornbeam charcoal (from a tree fifteen or twenty years old) Vio- 
lette got ash to the amount of 0.22% of the wood dried at 150°; Karsten 
got 0.32% and 0.35% by operating on the charcoal of young wood and 
old wood respectively. 
From horse-chestnut charcoal (from a tree 20 or 30 years old), Violette 
got ash amounting to 0.33% of the wood. 
From oak charcoal (from trees 10 or 12 years old), Violette got ash 
amounting to 0.09% of the wood; Karsten got 0.11% and 0.15% by ope- 
rating on the charcoal of old and of young wood respectively; and Ber- 
thier *'0.4%. 
As has been already intimated, most of these experiments were made 
upon charcoal from barkless wood, and since bark contains a very much 
larger proportion of ash than wood does, it is but natural that much less 
ashes should be found in wood from which the bark had been removed 
than in that which was burnt together with its bark. But while the 
absence of bark goes far to explain the small proportion of ashes found 
in wood by Violette, it does not appear that the differences between his 
results and those of the generality of observers can be wholly explained 
in this way. There will be found in the table above given, in several 
instances, determinations of the amounts of ashes obtained by burning 
wood by itself, without its bark, that may be compared directly with the 
results just cited. Thus, for example, Berthier, in his ‘‘ Voie Séche,’’ 
p- 256, found in oak sawdust free from bark, 1.1% of ashes; Sprengel 
found 0.21, 0.27, and 0.31% of ash in oak heart-wood, and 0.53% in the 
sap-wood. De Saussure found 0.20% in heart-wood, and 0.40% in sap- 
wood; and John found 0.67% in heart-wood. So, too, in heart-wood 
from hornbeam trees, Sprengel found 0.41% of ash, while De Saussure 
found 0.60% in heart-wood and 0.70% in sap-wood: figures which are 
notably larger than the 0.22, 0.32, and 0.35 deduced from the experiments 
upon charcoal, as just now cited. 
More evidence of this kind could readily be accumulated by contrast- 
ing Violette’s estimations of the ash in various other kinds of wood with 
kindred results in the table. It is true that many of these comparisons © 
will be found to be less precise than could be wished; that*sometimes the 
differences between the experiments of various observers, cited in the 
table, are as large as the differences between the results obtained by 
the two methods of incineration now in question; and that, in general, 
the proportion of ash obtainable in any way from barkless wood, is 
very much less than would be supposed at first sight on inspecting the 
figures of the table. Comparatively little is really known either as to 
the average amounts of ashes contained in wood proper (free from bark) 
or as to the average difference between ash determinations made upon 
charcoal and those made directly with wood; and it will hardly be pos- 
* “Essais par la Voie Séche,” p. 249. The comparatively high percentage of 
ash in this case may have been due to some admixture of bark with the wood. 
