112. In this Act:(1) the word “pneumoconiosis” shall mean a pathological condition of the lungs, due to breathing air containing siliceous dust and characterized anatomically by generalized fibrous changes in both lungs; such word includes, especially, the diseases known under the names of “silicosis” and “asbestosis” ;
(2) the expression “siliceous dust” shall mean silica dust or other compounds of silicon, including asbestos.