rocks, cemented together by calcareous matter, was observed.
The whole of the plain is covered, to the depth of
several feet at least, with white salt, principally borax,
which is obtained in a tolerably pure state by digging,
the superficial layer, which contains a little mixture of
other saline matters, being rejected. There is at present
little export of borax from Pugha, the demand for the
salt in Upper India being very limited, and the export
to Europe almost at an end.
It has long been known that borax is produced naturally
in different parts of Tibet, and the salt imported tnence
into India was at one time the principal source of supply
of the European market. I am not aware that any of
the places in which the borax is met with had previously
been visited by any European traveller, but the nature
of the localities in which it occurs has been the subject
of frequent inquiry, and several more or less detailed
accounts have been made public. These differ considerably
from one another, and no description that I have met
with accords with that of the Pugha valley. Mr. Saunders*
describes (from hearsay) the borax lake north of
Jigatzi as twenty miles in circumference, and says that
the borax is dug from its margins, the deeper and more
central parts producing common salt. Erom the account
of Mr. Blanef, who describes, from the information of
the natives, the borax district north of Lucknow, and,
therefore, in the more western part of the course of the
Sanpu, it would appear that the lake there contains bo-
racic acid, and that the borax is artificially prepared by
* Turner’s Tibet, p. 406. f Phil. Tr. 1787, p. 297.
saturating the sesquicarbonate of soda, which is so universally
produced on the surface of Tibet, with the acid.
At least, the statement that the production of borax is
dependent on the amount of soda, leads to this conclusion.
The whole description, however, (as is, indeed,
to be expected in a native account of a chemical process,)
is very obscure, and not to be depended upon. Mr.
Saunders does not notice any hot springs in the neighbourhood
of the borax; but in the more western district
described by Mr. Blane, hot springs seem to accompany
the borax lake as at Pugha.
It is not impossible that the three districts in which
the occurrence of borax has been noticed, which are only
a very small portion of those which exist, may represent
three stages of one and the same phenomenon. The
boracic acid lake may, by the gradual influx of soda, be
gradually converted into borax, which, from its great
insolubility, will be deposited as it is formed. On the
drainage or drying-up of such a lake, a borax plain, similar
to that of Pugha, would be left behind*.
Erom Pugha, two roads towards Le were open to us.
We might either return to the Indus, and follow the valley
of that river throughout, or proceed by a more direct
route across the mountains to join the road from Lake
Chumoreri to Le, by which Mr. Trebeck had travelled
on his way to Piti. As we knew that the Indus route
would be surveyed by Captain Strachey, who was desirous
of following the course of the river as far as prac-
* I have made over all my specimens of the borax and other saline
products of Tibet to Dr. It. D. Thomson, of Glasgow, who is at present
engaged in examining them.