(58 
effect would be produced only by carbonaceous substances. 
The influence of organic substances in the production of 
sulphides is further shown by the fossil remains, consisting 
of iron-pyrites, blende, copper-pyrites, variegated copper- 
pyrites, sulphide of copper and cinnabar.” This theory 
appeared to me to be open to serious objections, as it would 
be very difficult to show the presence of organic matter in 
many crystalline rocks sufficient to produce the large sul- 
phide formations often occurring in them through the reduc- 
tion of sulphates. I therefore desired to ascertain whether 
sulphuretted-hydrogen could be produced by simpler means, 
and in accordance with the occurrence of sulphides in rocks 
free from organic matter. With this view I placed some 
pure finely-powdered iron -pyrites into a glass tube, covered 
it with perfectly pure distilled water (previously well boiled 
in order to drive out any air dissolved in it), placed the tube 
and its contents in a vessel containing boiling water, heated 
it gently for a short time to drive out any air which might 
have been contained in the tube, and sealed the latter up. 
After heating the above in an air-bath for four days, at a 
temperature of about 120° C., the tube was opened, when a 
very strong smell of sulphuretted hydrogen was instantly 
perceived, and proved to be present by its chemical reactions. 
The liquid contents of the tube were analysed, and found to 
consist of ferric sulphate, ferrous sulphate, and free sulphuric 
acid, whilst there was a slight deposit of ferric oxide upon 
the sides of the glass tube. This experiment certainly 
proves that sulphuretted hydrogen can be produced in the 
interior of the earth without the presence of organic matter, 
as all rocks (both crystalline and sedimentary) contain more 
