Page:Popular Science Monthly Volume 81.djvu/182

176 In this connection I would say that in a paper read before the New York Section of the Society of Chemical Industry in November, 1897, and published in the Journal of the Society for January, 1898, I stated that, in my opinion as the results of investigations extending over eleven years:

Asphalt is in process of formation to-day. It plainly does not originate as such but is a secondary product resulting from the transformation of suitable lighter forms of bitumen, malthas or even thinner oils into harder bitumen by condensation and polymerization. A reaction in which sulphur, and probably sulphates seem to take an important part.

This conclusion was based on the fact that an ultimate analysis of the pure bitumen from fourteen solid asphalts from various parts of the world, showed the presence of from 9.76 to 4.78 per cent, of sulphur, while in the softer forms of bitumen which rapidly harden on exposure to the atmosphere, or on heating, notable amounts of sulphur, 2.0 per cent, or over are found.

The same conclusion seems to have been arrived at, independently and apparently without a knowledge of my investigations, by Dr. D. Holde, of the Royal Testing Laboratory near Berlin. In his book on mineral oils and fats he says:

A bitumen would be called native asphalt when it contains considerable amounts (2-10 per cent., usually over 4 per cent.) of sulphur not removable by