INDUSTRIAL PROBLEMS OF HEALTH 



383 



In polishing furniture powdered pumice stone and oil can be used 

 instead of sandpaper. 



In some dusty processes the machinery and the material are inclosed 

 in such a way as to prevent the escape of dust into the air breathed by 

 the workers — for example, in flour mills, in the crushing of ores and 

 minerals, and in the polishing of small metal objects. 



Fig. 168. Dust and safety hood 



In polishing metal goods this hood protects the worker from dust and, in case the 

 wheel bursts, from flying particles. (From a photograph furnished by the New Jersey 



Department of Labor) 



In grinding paints or metals it is possible in many cases to use a wet 

 process, in which water or oil holds down the dust particles resulting 

 from the grinding. 



Where it is not practicable to keep down the dust in the proc- 

 ess, special hoods connected with exhaust pipes are placed over 

 grinding wheels, over rotary saw blades, over polishing wheels, 

 and so on, to draw the dust away from the point at which it is 

 produced (Fig. 168). 



