354 BULLETIN OF THE BUSSEY INSTITUTION. 
tained when carbonate of lime and neutral chlorides or sulphates 
react upon one another, and he has noticed in experiments on to- 
bacco that a mixture of sulphate of potash and one third lime in- 
creased the luxuriancy of the development of his plants. He ob- 
served that a corresponding addition of sodium carbonate acted 
similarly, but that the effect of a larger amount of mere carbonate 
of lime was less favorable. 
As for the compaction of the soil due to this formation of the 
soluble alkali, Mayer testifies to the greatly diminished porosity 
(durchlissigkeit) of earth to which a mixture of lime and chloride 
of potassium had been added, and he alludes to the manifest re- 
semblances which subsist between this phenomenon and those pre- 
sented by certain loamy soils observed by him that had been oyer- 
flowed and soaked with sea-water. He cites moreover a number of 
instances, taken both from field-experiments and from farm-prac- 
tice, where mixtures of lime and Stassfurt salts have given better 
crops than were obtained from either of the materials taken sepa- 
rately ; and the very fact, which he insists upon, that there are nu- 
merous exceptions to this rule goes to show that not every kind of 
land is suited by such mixtures. Whence it seems to be not un- 
likely that they may act indirectly as ameliorants, rather than di- 
rectly as sources of plant-food. The fact that the Stassfurt salts 
have often been found to do good service on land that has been 
marled may here be brought to mind, as well as Mayer’s suggestion 
that mixtures of low-grade Stassfurt salts and lime are probably 
preferable in many cases to the potash salts by themselves, even if 
they are of high grades. 
Several different suggestions have been thrown out at one time 
and another in explanation of the apparent capriciousness of the 
action of mixtures of lime and Stassfurt salts, and it has been sug- 
gested by Wagner and others that such mixtures had better be ap- 
plied to the land in the autumn, in order that any chloride of cal- 
cium that may be formed shall be washed away by the winter’s 
rains. This view is supported by the results of Mayer’s pot-ex- 
periments, which show that the presence of chloride of calcium was 
hurtful as regards the soils used by him. But if it be true that one 
merit of such mixtures consists in their power of alkalinity, it may 
possibly sometimes be best to apply them in the spring, care being 
taken of course to select such kinds of soils as may need the alka- 
line treatment or can bear it. It will be well meanwhile to remem- 
ber Boussingault’s suggestion that the power of common salt to 
