M. Beudant on the Natron Lakes Hungary. 
tain depth, along with the different salts with which it is inixed$ 
and that the waters, by filtering through the mass of earth, in 
order to regain their level, laid hold of those substances, which 
they carried to the surface of the soil. This opinion is, in fact, 
that which would naturally present itself to the first observers, 
because it is the most simple ; but it cannot be supported by 
any positive observation, because no pits have been dug which 
might confirm it, in the different places where the natron ap- 
pears at the surface of the soil. But farther, there is no analo- 
gy to give it countenance ; for nowhere, in the deposits of rock-> 
salt, whether of the more ancient or more modern kind, is carbo-^ 
nate of soda found ; and, lastly, the waters of our seas which depo- 
sit their salt upon the shores, are equally destitute of any traces 
of it. Now, we find, however, that in this latter case, natron 
also is formed, although in small quantity, efflorescing at the 
surface of the soil ; and here its origin cannot be attributed to 
any thing else than the decomposition of the muriate of soda. 
We know in fact that this decomposition may take place 
through the agency of several means which differ from each 
other only in the quickness or facility witlf which they operate. 
Advantage has been taken of this in the manufacture of artifi- 
cial sub-carbonate of soda, jin which several methods, more or 
less advantageous, have been successfully employed. 
It is, therefore, also in the natural decomposition of muriate 
of soda, that we are led to seek the origin of the natron which 
occurs in such abundance in the vast plains of our Continents. 
It is thus that M. Berthollet has explained in a manner extreme- 
ly probable, the formation of this salt in the valley of the natron 
lakes in Egypt. This learned chemist has shown, that it is 
owing to the reciprocal action of the muriate of soda and carbo- 
nate of lime, assisted by the efflorescence, which determines the 
successive separation of the carbonate of soda ; and which, by 
this means, allows the decompositon to go on ad mjinitum. The 
inspection of the places gives every probability to this explana-^ 
tion; for the lakes contain a great quantity of muriate of soda, 
and they occur in the midst of a calcareous formation, the 
rocks of which project here and there through the sand which 
cover them ; masses or beds of gypsum also occur, which 
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