BULLETIN OF THE BUSSEY INSTITUTION. 249 
tion is strictly correct, or that the details of it can fairly be cited as if 
they were of the same general order as the results given in the table. 
On comparing the percentages of ash, given in the table above, that 
have been got directly from wood, with the results now in question, 
that have been obtained from charcoal, it is hard to escape the convic- 
tion that the latter do not indicate the whole of the ashes that the 
woods really contained. It would seem that the absolute amount of ash 
in charcoal is almost always a little less than the amount of ash in the 
wood from which the coal was produced. 
There was undoubtedly something of truth in the old notion of Neu- 
mann, Wenzel, and other of the early chemists,* that wood burnt in the 
open air yields more ‘‘ salt ’’ than can be got from the charcoal obtained 
from a similar amount of wood. Even the opponents + of this view have 
shown that a certain amount of earthy, non-volatile matters are always 
lost during the distillation of wood, especially when the distillation is 
rapid, and the escape of the volatile products tumultuous. Braconnot t 
found 274 per cent of ashes in powdery soot from wood smoke, taken 
from the middle of a chimney, and in lamp-black he found 2% of ash. 
Violette § goes so far as to assert from the results of his own experience, 
that ‘‘ it must be admitted that, in the ordinary processes of carbonization, 
the matters that separate by volatilization carry off about 3% of mineral 
‘matters, either mechanically or in a state of combination with hydrogen.’’ 
It is to be noted, however, that the experiments upon which Violette || 
specially bases this conclusion may perhaps have been vitiated by mat- 
ters derived from the glass tubes in which the trials were made. 
The following examples, taken at random, may serve to indicate the 
difference between the amounts of ash obtained by incinerating charcoal 
and those obtained directly from wood. On burning the charcoal 
obtained from 100 parts of wood from birch-trees, 10 or 12 years old, 
Violette found enough ash to amount ‘to 0.30% of the wood dried at 
150°. Berthier (‘‘ Voie Seche,’’ p. 249) found 0.30% of ash by operat- 
ing on the carbon of air-dried wood; and Karsten got 0.25% and 0.30% 
accordingly as he operated upon the wood of young or of old trees. But 
all these numbers are much smaller than those, given in the table above, 
that have been obtained by the direct incineration of birch-wood. 
From the charcoal of the wood of a grape-vine, 10 or 12 years old, Vio- 
lette got only as much ash as would amount to 0.10% of the wood dried at 
150°. But from the table above it appears that 3% or more of ash has 
usually been met with in dry vine-wood. 
* See John’s “ Ernahrung der Pflanzen,” Berlin, 1819, p. 8. 
+ For example, Wiegleb and John. See the latter’s “‘ Ernihrung der Pflan- 
zen,” pp. 23-25, and note. 
¢ “ Annales de Chimie et de Physique,” 1826, 31. pp. 50, 57. 
§ “ Annales de Chimie et de Physique,” 1851, 32. 332. 
| Loe. cit. pp. 326-382. 
VOL. I. 32 
