Relation to Chalk and Mineral Salts. 
69 
Baumann and Gully (’ 10 ) connected this acidity of Sphagnum with the 
well-known acidity of peaty soils. Peat consists largely of imperfectly 
decomposed Sphagnum , and it seemed probable that the acid of the peat 
was the acid of the Moss. They determined the acidity of the Sphagnum 
and of the underlying peat, and found in one case : 
Sphagnum . . . 0.228 grm. acid hydrogen per 100 grm. 
Peat .... 0.260 grm. acid hydrogen per 100 grm. 
This relation was found to be quite general, the two agreeing closely, 
with the peat somewhat higher. That the two would be exactly the same 
was not to be anticipated; the peat contains much foreign matter, and on 
the other hand the plant remains in it are much altered and partly 
decomposed. 
Baumann and Gully proceeded to investigate the nature of the acid 
substances. They started with an old observation of Sprengel’s, confirmed 
by various other workers, that peat is able to decompose and render 
soluble tricalcium phosphate. They worked out the reaction between 
that compound and peat and Sphagnum. Both decompose it in precisely 
the same way, and to about the same extent. The reaction is very 
interesting, as the calcium compound is almost insoluble—according to 
Rindell (’ 99 ) 132 mg. P 2 0 5 per litre—and it must be supposed that suc¬ 
cessive small quantities go into solution and are attacked by the organic 
compounds of the peat (or Sphagnum ). Part of the phosphoric acid appears 
in the solution as such, part as monocalcium phosphate; part of the calcium 
is removed by the peat. The reaction consists essentially of a splitting 
up of the phosphate with removal of the base and liberation of the acid. 
The formation of the monocalcium salt may be regarded as secondary, 
due to action between the liberated acid and the undecomposed phosphate. 
To show the extent of the solvent action we may give the following 
figures: 
Of tricalcium phosphate with 1,200 c.c. water, 158 mg. P 2 0 5 . 
„ „ „ 1,200 c.c. water+ 6 grm. Sphag- 
num, 1,383 mg. P 2 0 5 . 
?, » „ 1,200 c.c. water + 6 grm. Peat, 
T 5 61 mg. P 2 0 5 . 
The observations were extended to other salts, and the remarkable 
result was obtained that, with the exception of the extremely insoluble 
calcium oxalate, all the salts tried were broken up with liberation of the 
acid of the salt. The amount of acid hydrogen liberated from the various 
salts tested, by 100 grm. dry peat or Sphagnum , is given in Table III. 
^ * 
