22 Professor Bischof s Reasons against 



fatara. The solfatara near Fuzzuoli, and many in the Andes, 

 present sufficient instances of this kind. 



This circumstance seems to me the most fatal to the che- 

 mical theory. I cannot imagine how its advocates can remove 

 this difficulty. They will not surely be disposed to assume 

 that the hydrcgen separated by the decomposition of water, 

 in the first phasis of volcanic action, is reserved in vast ca- 

 verns near and about the focus of the volcano, and that it is 

 only a long time afterwards that the combination with sulphur 

 takes place ? 



I am quite at one with Professor Daubeny, in admitting the 

 large beds of sulphur which exist in most volcanic districts 

 (viz. Sicily), to be the result of the decompositions of the sul- 

 phuretted hydrogen evolved. Many years ago I stated in 

 German journals, and, I think, on good grounds, that these 

 beds, both in volcanic and neptunian districts, may for the 

 most part have been generated by the slow oxidation of sul- 

 phuretted hydrogen at the common temperature, at the ex- 

 pense of atmospheric air, whereby only the most oxidisable 

 ingredient of it, the hydrogen, was oxidised, whilst sulphur 

 was deposited. Regarding the formation of sulphuretted hy- 

 drogen, there is, however, a difference of opinion between 

 Daubeny and myself. He remarks, that I pass over without 

 any attempt of explanation, among other things, the evolu- 

 tion of sulphuretted hydrogen, in quantities far exceeding 

 what are to be explained by the reaction of carbonaceous 

 matter upon sulphates, or any of those other processes which 

 sometimes produce it on the surface of the earth. 



Though intending to discuss this subject in my future pub- 

 lications, yet I may take this opportunity of answering these 

 remarks of Professor Daubeny. 



Sulphuretted hydrogen seems generally to be formed by the 

 reaction of carbonaceous matter upon sulphates. There are 

 many instances which appear to lend considerable weight to 

 this supposition. Thus mineral waters containing sulphates 

 disengage sulphuretted hydrogen, when for a long time in 

 contact with any organic matter, for instance straw. I once 

 put a tea-spoonful of sugar in such a water, placed in a pitcher. 

 After having allowed it to remain four years in a cellar, such 

 a considerable quantity of sulphuretted hydrogen was gene- 



