SECTION 1. Section two of Act Numbered Forty-one hundred and twenty-three is hereby amended to read as follows:
"SEC. 2. This Act shall apply to the following laborers and classes of laborers:
"(a) Stokers and laborers exposed to the heat of foundries, forges, and boilers or employed in rooms where ordinarily a high temperature is maintained;
"(b) Those exposed to the action of deleterious gases or working under conditions injurious to health;
"(c) Those using or handling explosives or harmful substances or employed in the production thereof;
"(d) Laborers employed in quarries, mines, or underground work;
"(e) Those who operate or work with machinery of such size, power or condition that it may cause death or serious injuries in case on an accident;
"(f) Those working with steel, iron, and other heavy metals in foundries and construction or repair shops;
"(g) Those employed in loading and discharging ships and in similar work in warehouses;
"(h) Divers, sewer workers or those exposed to dampness and wet conditions;
"(i) Those employed as electricians and linemen or working with electricity of high voltage in public utility enterprises;
"(j) Painters, window washers, roofers, construction workers of tall buildings and ships and other construction of sufficient height as to cause death or serious injuries in case of fall;
"(k) Drivers of automobiles, trucks, street cars and locomotive engines in public utility enterprises and air service pilots."