684 TEANSACTIOyS OF THE AMERICAN INSTITUTE. 



wliicli are simply plots of hard packed eartli, on which the material 



is spread out to be dried by the action of air and sunlight. At those 



seasons when the floors cannot be used, and also in long periods of 



wet weather, the drj^ng is performed in kilns constructed for the 



purpose. But this is so expensive that every Aveek of sunshiny 



weather saves the company $500. The uncertainties of the weather 



constitute, indeed, one of the drawbacks in the business, for if fine 



and warm a "floor" may be properly dried in two days, whereas, 



otherwise, it may require a month. It should be mentioned that in 



order to facilitate the drying, the mass on the floors is gone over at 



intervals with a plow or cultivator, which loosens its texture, and 



favors the escape of moisture. 



When the dried night-soil is taken from the floors, it constitutes a 

 ' . . . 



dark, friable substance, its bad odor is removed by the action of the 



acid, and it is now ready for the mills, by which it is reduced to a fine 

 dust. The mills have shafts whicli rotate at a high speed, and are 

 furnished with iron blades or arms, pivoted at their inner ends 

 to the shaft, but capable of swinging, so as to yield in the event of 

 striking any bit of hard rubbish that ma}^ not have been previously 

 separated from the material. These shafts, with their blades or arms, 

 are inclosed within cylinders having openings at the top, into which 

 the material is throwni \y elevators, and other openings at the bot- 

 tom, which enable the milled material to pass to sets of shaking 

 screens, which separate it into d liferent grades of fineness. Tlie 

 mills are located- on the second floor of the building, each one being 

 furnished with an endless chain elevator extending downward to the 

 floor beneath, where a great heap of the dried night-soil is placed in 

 suitable pn-oximity to the elevator. The elevator is provided with 

 buckets or boxes, like those used in the elevators of grist mills, but 

 much larger, each bucket holding perhaps half a bushel. A man 

 with a dung-fork throws tlie material into the buckets as they are 

 carried upward by the movement of the apparatus. The buckets 

 empty their contents into the mill above. The material passes 

 through the mill, and is reduced to a finely jDOwdered condition, and 

 falling upon the vibratory screens before mentioned, is separated into 

 three parts, the first and second grades of poudrette, and the«rubbish 

 that may have escaped the sepai-ating process at the outset. The 

 two former are fertilizers ; the latter, of course, is waste, and is com- 

 posed of cinders, sticks, pieces of brick, &c. The poudrette, as it 

 comes from the mill, is a fine uniform powder, having a grayish 



