THROUGH ASIA 
1 6 
throuph the much-dreaded desert between Sa-chow and 
o 
the lake. 
Basing his deductions partly on certain geological laws, 
and partly on a large map of China and Central Asia 
published in Wu-chang-fu in 1862, Von Richthofen 
says : — 
“ The most remarkable thing about Przhevalsky’s Lop- 
nor is, that he discovered a freshwater lake, where we are 
constrained to assume the presence of salt water. It is an 
absolute impossibility that a lake-basin, which for a series of 
geological periods has acted as a reservoir for the deposi- 
tion of salt from a great river, should contain fresh water 
and be the resort of fish. This would be inconceivable 
even though the whole course of the Tarim lay through 
regions which in the general estimation were quite free 
from salt. But as a matter of fact all the regions whence 
the lake gathers its drainage are so saline that freshwater 
springs are quite an exception, and occur only close to the 
foot of the mountains. Now the water of the Tarim must 
contain a greater quantity of salt than almost any other 
large river in the world. The concentration of these 
saline ingredients by evaporation must take place to a very 
great extent in the last reservoir of the Tarim, and the 
continuation of the process from time immemorial must 
therefore have caused an unusually large deposit of every 
kind of steppe salt. From the remotest ages the Chinese 
have called Lop-nor ‘ the Salt Lake.’ . . . Contrary to all 
theoretical conclusions and historical accounts, we now have 
from the first European eye-witness, who is furthermore 
gifted with uncommon powers of observation, the distinct 
assurance that the last basin of the Tarim is a freshwater 
lake. There must therefore exist peculiar circumstances to 
account for this apparent contradiction.” 
It might perhaps be supposed that during the winter, 
when the evaporation is slight, the fresh water rises and 
spreads above the salt water ; but the inconsiderable depth 
of the lake sufficiently nullifies this supposition. Another 
explanation is that the Tarim, which often changes its 
channel, has abandoned its former reservoir in favour of 
