356 MILL AND ELEVATOR INSECTS 



can be cleaned and used again. These crocks, after being cleaned, 

 are in no way injured for household use later by having been used 

 for this purpose. 



Small mills that is, mills in which there are not more than 

 ten or twelve jars on a story may be treated by dropping the 

 charges by hand. We find that, under ordinary conditions pre- 

 vailing in mills, about twenty-five seconds elapse between the 

 dropping of the charge and the giving off of the fumes in fatal 

 quantity. Where the floor is not too much obstructed by spouts 

 or machinery, two level-headed men can walk rapidly from jar to 

 jar, dropping a bag in each jar, and descend to the floor below 

 without delay, closing the trap-door, or improvised cover of build- 

 ing paper, as they go down. Ten jars could easily be treated thus 

 in less than twenty seconds. In other words, the men would be 

 in the story below before the jar first treated began to give off a 

 dangerous quantity cf the gas, and as the gas always ascends, 

 being lighter than air, operators on the floor below are, for a 

 while, perfectly safe. Large mills, however, have to be strung. 



Stringing a large mill consists in running stout cords, such as 

 window cord, from the ground outside the building to various 

 windows on each floor. One set of cords intended for lowering the 

 cyanide is passed into the building, and the other set of cords so 

 attached to the windows that they can be pulled down or lowered, 

 after the process, thus insuring complete ventilation before the 

 mill is entered. 



The cord by which the cyanide is lowered into the crocks, after 

 being passed through a hole in the window casing above the win- 

 dow, is continued through a strong screw-eye fastened to the 

 ceiling or beam twelve or fifteen feet from the window. Smaller 

 strings, each capable of supporting a weight of eight or ten pounds, 

 are fastened to this cord after it has passed through the screw-eyes. 

 The number of strings attached to all the cords entering a certain 

 story should correspond to the number of three-pound packages 

 of cyanide to be used on that flocr. These smaller strings should 

 run off in various directions, in order that the charge may be well 

 distributed, care being taken to so arrange them as to avoid 

 friction with any machinery. . These strings should be passed 

 through convenient screw-eyes, each one finally hanging to the 

 floor at the point decided upon for the placing of a jar. 



The first screw-eye near the window, through which the heavy 

 cord passes, should be large enough to receive two of the heavier 



