170 The Composition of Peat, and Ecological Methods. 
moisture still retained in air-dry peat depends upon many 
factors; time, temperature, humidity of the atmosphere, 
fineness of division of the peat when drying, and so forth; 
these factors introduce such a large ‘personal equation’ 
into the manipulation, that results could scarcely be considered | 
concordant unless great detail in method employed were ob- 
served. It is, however, gratifying to know that ‘ without a 
knowledge of the humus-content, the water-content, was 
meaningless ’—which is not very surprising ! 
Turning to the humus-content, we do not fare much 
better, for evidently ‘humus’ is not identical with ‘ humus- 
content,’ as will be seen presently. The ‘humus’ is generally 
represented by ‘loss on ignition ’—or as it is often called, 
“the organic and volatile matter,’ and this for all practical 
purposes is equal to the moisture-free peat—as good peat con- 
tains only a small amount of ‘ mineral matter’ or ‘ash’ 
(see appended analyses), But the author says ‘The ratio 
_Humus . 1 ; f 3 by: th in é 
Winer is alSO a convenient way O expressing (S umus- 
content ’—this may be so—but one ventures to suggest that 
Humus /ess Mineral would be a much more accurate way ! 
The magnitude of this error may be readily understood from 
results given in the author’s analyses (B. A. Report, p. 582; 
The Naturalist, p. 362), where ‘Pure Eriophorum-Moor Peat 
contains humus 8o per cent., and ash 2 per cent. ; this, accord- 
ing to the ‘ convenient method’ has a humus content of 8! or 40, 
instead of 80 less 2, or 78. While in the Transitional Eriophorum- 
Moor Peat containing 50-80 per cent. humus and mineral 
matter 10-40 per cent. the discrepancy will be even greater. 
If the above be the method of obtaining the humus and water- 
Water-content 
Humus-content 
contents of peat, what can be the value of 
hus obtained ? One indeed can scarcely imagine, but it is 
very satisfactory to learn that it ‘reduced them to order.’ 
In addition to the above ‘ water’ figures there is still some 
uncertainty as to which represents the physiological water- 
content of the peat ; and further, one would naturally expect 
that in determinations made on acidic peats to find at least 
some relative indication of the amount of acidity, if not the 
actual amount, present ! 
In order to correct any false impressions about the com- 
position of peat, and to illustrate the method usually adopted, 
the following analytical details of two samples of peat obtained 
from our Yorkshire Moors may be found useful. 
The first column in each case gives the results obtained on 
analysis of the sample as taken ; the second column the same 
results but the percentages are calculated on the dried peat and 
here, naturally, the moisture does not in any way enter into the 
Naturalist, 
