BULLETIN OF THE BUSSEY INSTITUTION. 197 
it in a little flask provided with an abduction tube, the outer limb of 
which dips in lime water, acidulating the contents of the flask, and 
then heating them, carbonic acid will distil over into the lime water, 
and there yield an abundant precipitate. Even when the extract of 
earth is simply boiled in the flask without acidification, a quantity of 
carbonic acid will go forward and react upon the lime water. On 
the other hand, the presence of lime in the earth extract — and in the 
precipitate also that is produced by adding ammonia water or the like 
to the extract —is readily shown by testing with ammonium oxalate. 
It is not in the first drops, merely, of the filtrate that carbonate of 
lime may be found. On the contrary, the subsequent fractions of the 
percolate contain an abundance of it. Indeed, the process of washing 
out the carbonate is usually extremely tedious. It would hardly be an 
exaggeration to assert of some of the air-dried loams examined in this 
laboratory that so long as a supply of water is maintained at the top 
of the column of earth a solution of carbonate of lime will drop from 
the bottom of the column; though, naturally enough, some of the earlier 
fractions of the percolate contain a larger proportion of the carbonate 
than those which come afterward. ‘These remarks are, of course, 
meant to apply particularly to ordinary loams or cultivable soils. 
When the soil experimented upon is of exceptional or extreme char- 
acter, such as peat or sand, for example, the small amount of lime 
contained in it will be quickly washed out, and it is only in the first frac- 
tions of the percolate that the reactions of carbonate of lime can be 
obtained. With pure sand the reaction cannot be got at all. The 
following description of the behavior of loams that had been kept 
for several years in a dry store-room at the Bussey Institution, may 
serve to illustrate the foregoing statement. It may here be said, that, 
in all the experiments recorded in this article, the earths were sifted 
through a sieve whose meshes were 2 to 3 mm. in diameter before 
being placed in the percolators. 
I. Dry loam from the Plain-field of the Bussey Institution. A percolator 
7 cm. wide and 46 cm. high, having an effective capacity of about 
1,800 ec., was charged with the earth and percolated methodically with 
pure water, 850 cc. of which were absorbed before any drops of percolate 
appeared. Portions of each successive 50 cc. of the percolate were tested 
with ammonia water, with ammonium oxalate, with lime water added 
directly, and by boiling in a flask and conducting the steam into lime 
water, and reactions were obtained in every instance. The precipitate 
