595 
NATURE 
[| AuGUST 6, 1914 
INTERNATIONAL COMMISSION ON THE 
CHEMICAL ANALYSIS OF SOILS. 
MEETING of the International Commission on 
the Chemical Analysis of Soils was held at the 
Forestry Research Station, Munich, on April 23-24. 
Prof. Kraus, of the agricultural department of the 
Technical Highschool, Munich, was elected chairman. 
The first discussion, on the ‘‘ Preparation of Soil 
Extracts for Total Analysis,’’ was opened by Dr. A. 
von Sigmond (Budapest), who had prepared an ex- 
haustive account of previous discussions on the sub- 
ject at earlier meetings of the commission. The 
account is published in the Internationale Mitteilungen 
fiir Bodenkunde, 1914, and includes, in addition to 
the opinions of von Sigmond himself, articles by Dr. 
D. J. Hissink, Wageningen; Prof. E. W. Hilgard, 
Berkeley, California; and Prof. E. A. Mitscherlich, 
Konigsberg. The discussion centred round the rela- 
tive merits of :—(1) Hilgard’s Method, digestion of the 
soil for 120 hours with HCl of 1-115 sp. gr. on a 
water-bath; (2) van Bemmelen’s Method, division of 
the soil into two parts according to their solubility 
in HCl and H,SO,; (3) Ultimate Analysis (Bausch- 
analyse) by fusion with alkali, or treatment with HF. 
Hissink objected to Hilgard’s use of 1-115 HCl, and 
produced a ‘‘boiling-point ”’ curve for HCI of varying 
strength to show that Hilgard’s acid could not have 
the maximum solvent action, but that it lay with a 
rather stronger acid which had a higher boiling point. 
He gave the following results :— 
Sp. gr. of HCI ILLS 1°16 I'19 
Dissolved AI,O, 1-7 12-0 12-1 
ne Fe,O, 11-7 11-6 LI-7 
ay SiO, 25-0) Werke ese 25:3 
3 K,O 1-56 1-51 I-52 
and recommended van Bemmelen’s method as being 
the most complete for soil constituents likely to be- 
come available for plant food. 
Prof. A. Rindell (Helsingfors) gave results of esti- 
mations of K,O in felspar using varying proportions 
of felspar to acid :— ; 
Felspar gr./litre KoO gr./litre Per cent. of KgO 
50 Sot 0-144 ae 0:288 
100 Ae 0-258 0-258 
200 O-511 0:256 
300 1-034 0°207 
He recommended the ‘ultimate analysis” as the only 
one likely to give comparable results for all soils. 
Mitscherlich regards no method of strong acid 
extraction as valuable on the ground that the solution 
is affected by too many variables. 
The position was summed up by Prof. Ramann 
(Munich), who spoke in favour of much quicker 
methods, t.e. a shorter digestion with HCl, designed 
not to give a full analysis of all soil constituents, but 
of the more easily decomposable substances which 
may within a relatively short period become available 
as plant food. He contended that such analyses taken 
in conjunction with others, such as the estimation of 
easily soluble constituents, the mechanical analysis 
etc., would for all soils of the same type give accu- 
rately comparable results. ‘ x 
The members of the commission finally decided to 
unite in their efforts to obtain a standard method, 
and to investigate thoroughly the different methods 
side by side for their particular types of soils. 
The next discussion, led by Mitscherlich and 
Ramann, dealt with the ‘Estimation of the Easily 
Soluble Soil Constituents.” Mitscherlich advocated 
his well-known method of extraction with water 
saturated with CO,, the temperature, time of extrac- 
NOY 2336; VOL O34 
tion, quantities of water used, etc., all being constant 
during the extraction and for all soils. Ramann out- 
lined a new and interesting method recently tried 
by him, but not yet thoroughly worked out in detail. 
The water-containing double silicates of the soil 
can be separated into two groups: (1) those which 
permit of a quick, almost instantaneous replacement 
of their bases; (2) those with which the replacement 
of their bases takes place only very slowly. The bases 
from group (1) can be completely removed from a 
soil by the action of a fairly strong (10 per cent.) solu- 
tion of an electrolyte, provided that the experiment is 
so arranged, that the soil is continually in contact 
with the fresh solution, or, in other words, that the 
dissolved bases are immediately removed. This is 
carried out by allowing the electrolyte solution to 
filter slowly through a column of soil in a vertical 
glass tube. Ramann found that by taking 25 grams 
of soil and a to per cent. solution of ammonium 
nitrate the whole of the easily replaceable bases of 
group (1) was contained in the first 50 c.c. of the 
filtrate. The following quantities of 50 c.c. contain 
a very small proportion of replaced bases, the quantity 
of which represents the equilibrium between electro- 
lyte solution and the silicates of group (2). For 
example, the proportions of CaO, MgO, K,O, Na,O 
obtained in the first, second, third, fourth, and fifth 
50 c.c. of filtrate for 25 grams of soil were as 
follows :— 
co MEM 
CaO 0-403 0029 0-049 0:042 0-030 
MgO 0-076 0002 0-009 0-008 0-004 
K,O 0-013 0-002 0004 0:002 0:003 
Na,O 0-012 0-003 0:00 0-00 0-002 
3 
Ramann is of the opinion that these easily replace- 
able bases represent the bulk of the available mineral 
matter in soils, and therefore proposes that this should 
be estimated. 
To obtain further information as to the bases in 
soils most easily attacked and set free by weak acids, 
and as to the easily soluble P,O,, Ramann makes use 
of water containing CO,. The extraction is carried 
out in a large Soxhlet extractor; the water is boiled 
and condensed in the usual way, and the CO, is led 
directly into the thimble containing the soil. ‘ihe 
stream of CO, is constant, the temperature is kept 
as constant as possible (between 60° and 70° C.), and 
the burner arranged so that the syphon works every 
go minutes. The extraction continues for ten hours, 
when practically all solvent action has ceased. 
Ramann recommends that the two estimations should 
be made simultaneously. 
These methods called forth such universal interest 
that practically all members took part in the dis- 
cussion following, and unanimously requested a 
demonstration of the methods, which was given at the 
end of the conference in Ramann’s laboratory. The 
remarkable part of the discussion was that no method 
involving the use of organic acids, such as citric acid, 
was even mentioned. The methods of Hall and Dyer, 
and the American official method, used almost exclu- 
sively in England and America respectively, appear to 
be very little used on the Continent. 
It was unanimously decided that for the purposes 
of the commission, 1.e. the arrangement of standard 
international methods of soil analysis, members should 
for the present confine their work to extractions with 
water and CO.. 
The discussion on methods for the ‘‘ Estimation of 
Acidity in Soils’? was opened by Dr. Gully, of the 
Research Station for Moor Cultivation in Munich. 
; He gave’ an account of the methods tried jin his 
