M, Beudant on the Natron Lakes of Hungmy, 
burg and of Oedenbiirg ; but it is more particularly between 
Debretzin and Nagy-varad that it has long been obtained, in 
lakes which dry up in summer, and where it also effloresces at 
that season on the surface of the ground. These saline efflo- 
rescences, which in the middle of summer resemble heaps of 
snow, have given rise to the name of White Lakes (Fejer to) 
which is applied to those marshes. They are renewed at the 
end of three or four days after being removed ; so that, during 
the whole summer season, considerable quantities are collected, 
which are afterwards carried to Debretzin, as well for the ma- 
nufacture of soap as for exportation. It appears that the quan- 
tity collected annually amounts to upwards of 10,000 quintals, 
and an infinitely greater quantity might be obtained^ as there 
are very many rich lakes which are neglected on account of the 
remoteness of their situation. 
Similar Lakes known in other Parts the Globe . — The ex- 
istence of natron in the midst of plains, in the waters of lakes 
and marshes which cover them, is one of the most interesting 
facts in geology. It is not in Hungary only that this pheno- 
menon presents itself ; we find it every where in the midst of the 
vast deserts which occur in so many places on the surface of 
our globe. All that we know of this mineral production in 
Egypt, in Arabia, in Persia, in India, in Thibet, in China, in 
Siberia, in the plains of the Caspian and Black seas, in Asia 
Minor, and at Mexico, evinces that every where it occurs with 
the same relations, and in the same circumstances ; every where 
is it found in the midst of sands mixed with marl and clay, and 
is accompanied with many other salts, of which the most con- 
stant is common salt. Those natron lakes of Hungary which 
are the nearest to us, and those vi hich may be visited with most 
facility, were well adapted to excite my curiosity ; but it is very 
difficult to collect, in the midst of those plains, which do not 
present a single ravine, a sufficient number of facts to lead to 
the solution of all the questions which might be proposed. I 
have returned to Debretzin with as little certainty on this sub- 
ject as when I left it, even after perusing the indications pre- 
sented by various publications regarding it ; the continual rains 
which had previously taken place, had so broken up the 
