1865.] Notes on Central Asia. 133 
the neighbourhood of Kuldja, in large quantities, from very deep 
seams. The whole process of the formation of sulphur can then in my 
opinion be reasonably explained by the combustion of some coal seams 
in this basin, which would at once set at rest the question of supposed 
volcanic agency. 
I cannot positively affirm that the origin of the other smoking pits 
of Djungaria, and particularly Humboldt’s famous “ Solfater’ of 
Urumchi, is susceptible of the same explanation, although the analogy 
between all the Djungarian ‘“ Solfaters’ would appear to be confirmed, 
native accounts excepted, by the circumstance that the Chinese, who 
are very expert in recognising such sulphur formations, procure sulphur 
from the “ Solfaters” of Kati which I visited. 
With still less certainty can I deny the existence of volcanic pheno- 
mena or volcanic forms farther eastwards in the Celestial mountains. 
Humboldt in his observations on the letter I addressed to Ritter, 
which was published in the “‘ Zeitschrift fir Erdkunde” says that the 
Sangai, rising in the centre of the Ando-Cordilleras range, the most 
active of all the volcanoes in the world, forms around itself an island 
of trachyte, not more than two geographical miles in diameter. From 
this I must of course conclude that the observation of a single portion 
of the Tian-Shan visited by me cannot serve as a positive evidence of 
the absence of volcanoes and volcanic forms in other parts of this 
mountain system. My conclusions on this question generally have 
already been made public, in the letter here referred to, but I must 
likewise observe in addition, that all Asiatic accounts of phenomena 
which might be volcanic in appearance, should be treated by men of 
science with great circumspection, as many of these accounts have 
already proved fallacious. I would here also remark that the impres- 
sion produced on me personally by Djungaria and the Tian-Shan 
leaves great doubts in my mind as to the existence of volcanoes in this 
part of Asia, and as I am the only traveller who has visited the 
Tian-Shan, I cannot accept the belief in their existence, as an axiom 
requiring no proof or confirmation. 
My conclusion on this point, though negative, is one of the most 
important results of my journey. 
If, in aspiring after the truth, I have been compelled to express 
opinions on two points of such vast importance to the geography of 
