Analyses of the Aslics of Plants. 
127 
A notice on this subject appeared about the same lime 
from the pen of Professor Milscherlich, another Continental 
chemist of high repute. The evidence adduced by Professor 
Milscherlich was similar in character to that brought forward by 
Rose, and tended to the same result, namely, that the usual 
methods of burning preparatory to the analysis of ashes did not 
afford correct results. Both these chemists proposed for future 
adoption particular methods of combustion to obviate the errors 
which they had then pointed out, and insisted upon the neces- 
sity of pursuing amended plans in all analyses of aslies intended 
to be used in the deduction of scientific principles, either in 
vegetable or animal physiology.* 
The j)ublication of these results, together with a feeling existing 
in the minds of English chemists, of the unsatisfactory nature of 
the evidence on the whole subject, left us, in our opinion, no alter- 
native but to institute a rigorous examination both of the methods 
of preparing and of analysing plant-ashes. We felt that it was 
due to the Society who have intrusted this subject to our care, 
previously to the publication of any further results, to ascertain by 
careful experiment how far the ash of a plant, prepared as we 
are in the habit of preparing it, really represents the actual 
mineral matter of the vegetable product under examination. 
The decision of this point has, as every chemist w ill under- 
stand, only been accomplished after the expenditure of A'ery much 
labour and time, but it has resulted in the conviction of our own 
minds that, zcith one exception, the ordinary methods of burning, 
when carefully conducted, give ashes which, not only for all 
practical purposes, but for scientific deduction, may be taken to 
represent accurately the mineral composition of vegetable sub- 
stances in general. 
The single exception (and it is certainly a most important one) 
is that of sulphur. No sjstem of ordinary burning, however 
slowly or carefully conducted, is capable of giving the true quan- 
tity of sulphur, or, indeed, any approximation to the true quantity, 
in vegetable substances submitted to examination.! 
In this respect all the analyses hitherto published are, in com- 
mon with our own, open to objection ; but it is satisfactory to 
* We may mention by the way, although with every deference for the 
judgment of the great authorities in question, that both of the methods 
proposed were far too operose, involved too much time and labour, to 
be at all applicable to the necessities of an investigation so extended as 
that of plant-ashes must necessarily prove ; neither, as we hope to show, do 
these plans ensure a gieafer amount of accuracy than is obtainable by 
very slight modifications of the ordinary processes. 
t Rose's method even is defective in this respect. 
