ORGANIC MATTERS OF THE SOIL. 231 
to solutions of humates or ulmates of the alkalies, precipi- 
tates are formed in which the acid is combined both with 
an alkali and an carth or oxide. These double salts are 
insoluble or nearly so in water. 
Solutions of alkalies and alkali carbonates decompose 
them into soluble alkali humates or ulmates, and the 
earths or oxides are at least partially held in solution by 
the resulting compounds. 
Mulder describes the following experiments, which justify the above 
conclusions. ‘‘Garden-soil was extracted with dilute solution of car- 
bonate of soda, the soil being in excess. The solution was filtered and 
precipitated by addition of water, aud the precipitate was washed and dis- 
solved ina little ammonia. Thus was obtained a dark-brown solution 
of neutral humate of ammonia. The solution was rendered perfectly 
colorless by addition of caustic lime—basic humate of lime is therefore 
perfectly insoluble in water. 
“Chloride of calcium rendered the solution very nearly colorless— 
neutral humate of lime is almost entirely insoluble. 
“Calcined magnesia decolorized the solution perfectly. Chloride of 
magnesium made the solution very nearly colorless. 
“The sulphates of protoxide and peroxide of iron, and sulphate of 
manganese, decolorized the solution perfectly. 
“These decolorized liquids were made brown again by agitating them 
and the precipitated humates with carbonate of ammonia.” 
Apocrenates and Crenates.—According to Mulder, the 
crenates.and apocrenates of the soil nearly always contain 
ammonia—are, in fact, double salts of this alkali with lime, 
i-on, etc. 
The apocrenates of the alkalies are freely soluble; 
those of the oxides of iron and manganese are moderately 
soluble; those of lime, magnesia, and alumina, are in- 
soluble. 
The ‘crenates of the alkalies, of lime, magnesia, and 
protoxide of iron, are soluble; those of protoxide of iron 
and manganese are less soluble; crenate of alumina is 
insoluble. 
All the salts of these acids that are insoluble of them- 
selves are decomposed by, and soluble in, excess of the 
alkali-salts. 
