1865.] Notes on Central Ash. 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 Katu 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 Bitter, 

 which was published in the " Zeitschrift fur Erclkunde" 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 



