Some time since, during the performance of a series of analyses of the Brown Coals of Otago, my attention was directed to the very large quantity of sulphur which several of them contained, even where the most careful examination failed to detect more than traces of sulphates or sulphides in the composition of the coal, a singular fact which has been before commented upon by Dr Percy in his work on Metallurgy.

After several unsuccessful efforts to discover the form in which the excess of sulphur was present, it occured to me, that possibly the sulphur might be retained to the coal in combination with hydrogen, by a similar absorptive power to that which charcoal exercises over that gas.