The Trials of Chist Mills and Disintegrators at Plymouth. G19 
things has already made the " Devil " the parent of certain 
entirely new industries. 
Among these there is, perhaps, no more interesting example 
than the conversion into manure of town and market refuse. 
Sheffield sends occasional contributions of mingled ashes, 
hampers, fish-bones, old boots, bottles, oyster shells, paper, 
vegetables, straw, and other "jetsam" to this ogre's den at 
Heeley, all of which, after going (with a pinch of lime for the 
sake of sanitation) through the " Devil's " maw, result in a 
digested mass of fertilizer, worth several pounds sterling per ton. 
Mr. J. Harrison Carter's disintegrator (No. 3403) was 
the next machine brought to test. This, as before explained, 
is a " Collision " mill, and consists of a cylindrical chamber of 
cast-iron, within which four radial beaters of the best Lowmoor 
iron, steeled on their working faces, revolve at a speed ot 
3,500 revolutions per minute. Substances fed into the mill 
are violently thrown, with a velocity of from 300 to 350 feet 
per second, against the inner wall of the cylindrical chamber, 
which consists, as to its upper half, of chilled cast-iron serra- 
tions, and, as to its lower half, of concave steel grids, or 
" screens," the fineness of whose mesh determines the character 
of the grinding. Twelve grids, advancing step by step from 
■^j to 2 inches, are used in practice, the mill being opened and the 
concaves changed as grinding of this or that degree of fineness 
is required. The beaters are disposed vertically, and are set to 
travel in three planes, covering the whole width of the beater 
chamber. They are driven through a countershaft by belting, 
and lie, together with the driving pulley, between the spindle 
bearings, which are long and adequate. The concaves, or grids, 
are built up of steel bars riveted, ladder-wise, to wrought-iron 
laterals, the " rungs " being few or many, according as the work 
to be done is coarse or fine. An " improved " grid was ex- 
hibited (though not used), wherein the rungs were merely 
slipped one by one into special laterals and secured therein by 
a locking-plate. The machine is well designed, and well and 
strongly made throughout, only the best materials and work- 
manship being employed — a necessity, indeed, where processes 
of such violence as those involved in a "Collision" mill are 
concerned. The disintegrator occupies an over-all floor-space 
of 3 feet G inches x 2 feet 6 inches, exclusive of counter-shafting 
and brackets, and weighs 1 1 cwt. 
The trial proper began on bones, of which 5£ cwt. were first 
served out, but the machine had not completed sixteen minutes' 
running when, warned by ominous noises, the exhibitor stopped 
it. On opening the mill it was found that a piece of iron 
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