OX THE CLEARING OF LAND FOR PLANTING. 139 



it is by far the most economical method of blasting stones. Hav- 

 ing used large quantities of it, I consider that it should always be 

 exploded by electricity, and as many charges as possible at one 

 time, for the gas evolved is highly injurious to those employed. 

 The charges should be fired about the time the workmen leave at 

 night. The gas will be dissipated before they return. 



