72 
Supplemmt to flip “ Tropical Agriculturist: 
[July 
back to their villages or other Agricultural Schools, 
and no one could be blind to the fact that very 
important results must follow from that in the 
course of time.” 
TRAVELLER. 
(To he continued.) 
9 
POTASH MANURES AND THE NEED FOR 
SPECIAL POTASH FERTILIZERS. 
( Continued.) 
The great .soufce of potash manures are the 
Stassfurt deposits. Ever since the beginning of 
last century the district of Stassfurt, in the 
province of Saxony, in North Germany, has been 
well known as the centre of a large s -It industry. 
The salt was formerly obtained l)y ]iumping up 
liquid frum wells, and evaporating it in pans. Th ■ 
discovery of solid rock salt had the effect, lioweve.-, 
of soon rendering this industry non-lucraf i ve ; and 
hence, in the year 1839, the Pnis.<ian Government 
instituted a series of iuve-tigations for the purpose 
of discovering wh.ether rock salt could not be found 
at Stassfurt. At fii’st the attempts were un- 
successful, but in 1857 a stritum of rock salt was 
discovered about 1000 feet below the surface. 
This deposit lay below a large layer of what were 
called Abraum salts (refuse salts), which consisted 
of compounds of j)Otash and magnesia. For a 
number of years little value was attached to these 
deposits, as their importance in agriculture at that 
time was not known. After a time, however, 
potash began to be extracted from these salts for 
use in various chemical manufactures. The value 
of potash as a manure for farm crops was also 
demonstrated by the rosearcb.es of Liebig, and its 
employment for this purpose became more and 
more extensive with the lapse of time. At the 
present time the potash industry in Stassfurt lia.s 
reached enormous dimensions, and every year tl'e 
amount of potash exported thence to all parts of 
the world for fertilising purposes is steadily in- 
creasing. Stassfurt has now become tlie centre of 
one of the largest manufacturing industries in 
Germany, and employs about 10 000 operatives in 
connection with potash mining and manufacture 
in Germany. Not much short of two million tons 
of Potash Salts are annually produced in the 
Stassfurt districts. 
It is believed that these salts were formed by 
the partial isolation of a sea, the waters of which 
.still maintained communication with the ocean for 
a long time, by means of small channels. This 
was thousands of years ago, and the climate of that 
part of Europe was then more of a tropical nature 
than it is at present. The result of these con- 
ditions was the steady evaporation of these 
partially isolated lakes of salt water, and tlie 
constant accumulation of the salt deposits. The 
less soluble salts were fir.st deposited, such as sul- 
phate of lime, ai;d in this way the lowermost layer 
of the do]iosit, which consists largely of this sub- 
stance, wa.s formed. Above this was deposited the 
rock salt. Thi.s stratum, which is about 3,000 feet 
deep, is estimated to have taken 13,000 years in its 
formation. In the upper regions of the deposit lies 
the potash hiyer, consisting largely of a mineral 
known as carnallit. which consists of muriate of 
potash and chloride of magnesia. This deposit is 
from 50 to 130 feet thick, and is the chief source 
of the potash salts. Above the potash there is a 
layer of impervious clay, which serves a very use- 
ful purpose in protecting the carnallit from being 
dissolved by the water, which would otherwise 
have been constantly percolating down through 
the soil ; indeed, had it not been for this layer of 
clay, it is highly probable that the potash, as well 
as the magnesia salts, would long ago have been 
washed out of these deposits. Above the clay lies 
another stratum of anhydrit, and above it a second 
salt deposit, which is of very much more recent 
formatioti than the first, and is characterised by 
its great purity. 
The enormous extent of these deposits may be 
estimated from the fact that their total depth 
amounts to about 5,000 feet, or nearly a mile ; 
while the deposits extend over an area of several 
thousand square miles directly east of the Harz 
mountains. Here and there, irregularities occur in 
the sequence of the different deposits. At some 
places surface water has enl ered, and, by its solvent 
action, dissolved out certain of the potash com- 
pounds, or changed them into other compounds. 
Hence, there occurs throughout the surface, depo- 
sists of such substances as kainit and sylvinit, both 
crystallised salts of potash, the former made up of 
a mixture of the sulphate and chlorides of potash 
and magnesia, and the latter of a mixture of muriate 
of potash, rock salt, and kainit. The extent of these 
deposits is so vast that they may be regarded as 
practically inexhaustible, or, at any rate, as suffi- 
cient to suj'iily the world with potash for many 
generations lo come. 
In Germany, quite a number of the raw potash 
salts are used for mauurial purposes, as they can 
be obtained very cheaply ; but the more concen- 
trated salts are preferred for export, owing to the 
greater relative expense incurred in the freight and 
handing of the impure forms The chief amount 
of potash exported is in the forms of the refined 
potash salts, viz., muriate and sulphate of potash, 
and in tiie less pure form of kainit. The com- 
position of some of the more commonly occurring 
crude potash salts is, however, deserving of notice. 
Carnallit, which is the most important, contains 
about 26 per cent, of muriate of potash. It is 
found of a variety of colours, caused by the ad- 
mi.xture of such impurities as iron, clay, and 
organic matters; and may be white, yellow, red, 
violet, grey, or even black. It is hardly ever found 
in the pure condition, and, as mined, generally 
contains only about 60 per per cent, of carnallit, 
the other 40 per cent, being made up chiefly of 
rock salt, kieserit, anhydrit and clay. It is sold 
for agricultural purposes in the form of a powder, 
and is guaranteed to contain at least 9 per cent, of 
potash, equal to about 14 per cent, of muriate of 
potash. 
Kainit, like carnallit, is found of a variety of 
colours, and never in the pure condition; but 
contains more or less rock salt and other im- 
purites. As sold for agricultural purposes, it is 
usually guaranteed to contain 12J per cent, of 
potash. 
Sylvinit is the third crude salt, and contains, on 
an average, 22 to .30 per cent, of muriate of potash. 
It thus sometimes contains more potash than 
kainit. 
