eee 
to be ground in Mr. Anderson’s mill are conveyed 
from the mill-floor to the upper part of the ma- 
chinery, by a series of buckets, attached to a 
double chain. They are discharged upon a sheet 
of canvass, extending over two revolving rollers, 
by the motion of which they are conveyed to two 
cast-iron rollers, to which are fixed concentric 
rings of malleable iron, with teeth, so as to present 
a serrated edge. The bones are thus partially 
bruised, and fall down upon a similar pair of 
rollers, but with the rings and teeth more closely 
set. Immediately underneath this second pair of 
rollers, is a riddle, kept in motion by a crank. 
The bones which have been completely ground 
fall through the riddle, and are received into a 
small division or apartment beneath. The rougher 
bones, or those which are only partially ground, 
-and have not fallen through, are conveyed by the 
motion of the riddle to a third pair of rollers 
formed like those above, but with their rings and 
teeth still more close. Immediately underneath 
these last rollers, is placed a second riddle, kept 
in motion like the other, through which the bone- 
dust falls directly into the division below formed 
_ to receive it, while any of the bones not suffi- 
ciently ground to pass through the riddle are car- 
ried forward by its motion into another apart- 
ment or division, from which they are either 
taken to be sold in their rough state, or are con- 
veyed up by the buckets as before, to pass again 
through the machinery. A paper in the portion 
of the Highland Society’s Transactions published 
in August 1829, whence we have borrowed our 
notice of this bone-mill, contains both vertical 
and front views of it, and a detailed technical de- 
scription. 
In some districts, the bones are crushed into 
the four different conditions designated, in refer- 
ence to the size of the largest pieces, inch, three- 
quarters-inch, half-inch, and dust,—the last being 
in a great measure collected by riddling the inch 
and the three-quarters-inch ; in other districts, as 
in Yorkshire, they are crushed into the three con- 
ditions of inch, half-inch, and quarter-inch or 
dust; and in others, as in Perthshire, they are 
crushed into only the two conditions of half-inch 
and dust. In the first of these methods, the inch 
and the three-quarters-inch kinds consist almost 
wholly of pieces from the maximum size of the 
designation down to about a quarter of an inch; 
the dust consists of a mixture of large grits and 
fine powder ; and the half-inch consists of a mix- 
ture of powder, grit, and pieces to the maximum 
size of the designation, and is generally and most 
justly regarded as considerably superior to any 
of the other varieties. In the second or York- 
shire method, the dust consists of everything 
which passes through a sieve of little more than 
a quarter of an inch in calibre; it contains all the 
sand and earthy matters accidentally lodged in 
the hollow of the bones, all the carious and rotten 
portions of the bones, and all the very old or par- 
tially decayed bones which are reduccd to powder 
BONE-MANURE. 
475 
by the first touch of the cylinders; it is much in- 
ferior in quality to the inch and the half-inch va- 
rieties, and acts for a much shorter period in 
the soil than they; yet it is heavier, comprises a 
much larger quantity of matter in a bushel, and 
will spread over a larger superficies of land ; 
and it acts more rapidly in pushing up turnips 
to a braird, and therefore operates, to a cer- 
tain degree, as a preventive against the ravages 
or even the attacks of the turnip-fiy. The half- 
inch variety, as prepared in the Yorkshire method, 
is free from the impurities of the more pulverized 
variety, and, when made from good bones, is, in 
most respects, superior ; yet when sown unmixed, 
it passes slowly into decomposition, and is tardy 
in pushing turnips to the braird. Whenever 
bones are crushed in the Yorkshire method, they 
will act most advantageously if the half-inch va- 
riety and the small variety be mixed in equal 
portions,—the latter to braird the turnips, and 
the former to operate durably in the soil. But 
the Yorkshire crushers mix them only when spe- 
cially ordered to do so; and then they measure | 
the two kinds separately, and, in consequence, 
give, in point of fact, little more than two bushels | 
under name of three,—the powder of the small | 
variety disposing itself in the interstices of the 
other variety. 
Bones from various parts of the continent, but | 
principally from those places whence they have 
been longest and most bulkily imported, are fre- 
quently so much adulterated with stones, hoofs, 
horns, and every kind of cheap or waste matter 
which will add to their weight, that they require 
to be handpicked before they can, with safety | 
to the teeth of the cylinders, be subjected to the 
process of crushing. But a vastly more mis- 
chievous adulteration is extensively practised by 
the crushers themselves,—one which not only in- 
demnifies them for the loss by foreign adultera- 
tions, but which sometimes imposes to a grievous | 
extent upon farmers, and indirectly occasions a 
serious paucity of crops. Some farmers, too, have 
an extreme fondness for finely pulverized bone- 
dust, and blindly afford the utmost facility for | 
the practice of the adulteration. One ingredient 
very extensively used, more extensively perhaps 
than any other, is the refuse lime of tan-works, | 
after it has been employed in removing wool and 
hair from skins. This is passed, in clotted lumps, 
into the cylinders of the bone-mill; it is freed 
from wool and hair, and mixed with a proportion | 
of bone-dust; and it appears very small, has a 
very pungent smell, and readily commends itself | 
to the unwary as prime bone-dust. “J am aware,” | 
observes Mr. Halkett, “that this mixture has 
often raised a good crop of turnips in damp sea- | 
sons. I have likewise known it destroy the seed 
entirely, when good bones beside it did well. I 
have no objection that it should be used as a 
manure for turnips; but why call it bone-dust, 
and not sell it for what it is? I once saw it used 
by itself, without any admixture of bone-dust, 
ae | 
