M I 1ST 
M 1 N 
198 
five inches broad, jointed, and containing 10 
or 15 seeds. These seeds are brown, shining, 
flattened, and very hard, and called cacoons. 
Tliey are the same as mentioned in the Philo- 
sophical Transactions, No. 222, page 298, by 
sir Hans Sloane, as being thrown ashore on 
the Hebrides and Orkneys. 
This bean, after being long soaked in wa- 
ter, is boiled and eaten by some negroes ; 
■but, in general, there seems to be no other 
use made of it than as a sort of sn uff-box. 
15. The catechu, according to Mr. Ker 
(Med. Obs. and Inquir. vol. v. p. 151, &c.), 
grows only to 12 feet in height, and to one 
foot in diameter ; it is covered with a thick, 
rough, brown bark, and towards the top di- 
vides into many close branches: the leaves 
are bipinnated, or doubly winged, and are 
placed alternately upon the younger branches : 
the partial pinna: are nearly two inches long, 
and are commonly from 15 to 30 pair, hav- 
ing full glands inserted between the pinnae: 
each wing is usually furnished with about 40 
pair of pinnulse, or linear lobes, beset with 
short hairs : the spines are short. From this 
tree, which grows plentifully on the moun- 
tainous parts of lndostan, where it flowers in 
June, is produced the officinal drug long 
known in Europe by the name of terra japo- 
mica. 
16. The nilotica, or true Egyptian acacia, 
rises to a greater height than the preceding. 
The fruit is a long pod, resembling that of 
the lupin, and contains many flatfish brown 
-seeds. It is a native of Arabia and Egypt, 
and flowers in July. Although the mimosa 
nilotica grows in great abundance over the 
vast extent of Africa, yet gum arabic is pro- 
duced chiefly by those trees which are si- 
tuated near the equatorial regions ; and we 
svtr told that in Lower Egypt the solar heat 
is never sufficientlv intense for this purpose. 
The gum exudes in a liquid state from the 
bark of the trunk and branches of the tree, in 
a similar manner to the gum which is often 
produced upon the cherry-trees, &c. in this 
country ; and by exposure to the air it soon 
acquires solidity" and hardness. In Senegal 
the gum begins to flow when the tree first 
opens its flowers ; and continues during tire 
rainy season till the month of December, 
when it is collected for the first time. An- 
other collection of the gum is made in the 
month of March, from incisions in the bark, 
which the extreme dryness of the air at that 
time is said to render necessary. Gum ara- 
bic is now usually imported into England 
from Barb ary, in large casks or hogsheads. 
The common appearance of this gum is well 
known ; and the various figures which it as- 
sumes seem to depend upon a variety of ac- 
cidental circumstances attending its transu- 
dation and concretion. Gum arabic of a pale 
yellowish colour is most esteemed ; on the 
contrary, those pieces which are large, rough, 
of a roundish figure, and of a brownish or 
reddish hue, are found to be less pure, and 
are said to be produced from a different spe- 
cies of mimosa ; but the Arabian and Egyp- 
tian gum is commonly intermixed with pieces 
of this kind, similar to that which comes 
from the coast of Africa near the river Sene- 
gal. 
Gum arabic does not admit of solution by 
spirit or oil ; but in twice its quantity of water 
it dissolves into a mucilaginous fluid, of the 
Consistence of a thick syrup ; and in this 
M 1 N 
answers many useful pharmaceutical 
Purposes, by rendering oily, resinous, and 
pinguious substances, miscible with water. 
The glutinous quality of gum arabic is pre- 
ferred to most other gums and mucilaginous 
substances, as a demulcent in coughs, hoarse- 
nesses/and other catarrhal affections, in or- 
der to obtund irritating acrimonious humours, 
and to supply the loss of abraded mucus, it 
has been very generally employed in e?ses 
of ardor urime and strangury ; but it is the 
opinion of Dr. Cullen, “ that even this mu- 
cilage, as an internal demulcent, can be of no 
service beyond the alimentary canal.” 
17. The Senegal is a native of Guinea, and 
was some time ago introduced into Jamaica. 
The flowers are globular, yellow, and fra- 
grant. The pods are brown, and of the size 
of a goose-quill. The tree, on being wound- 
ed, exudes gum arabic, though in less quan- 
tity, and less transparent, than that of the 
shops, which is obtained from the nilotica 
above described. 
There are above 40 other species charac- 
terised in the Systema Vegetabilium. 
M1MULUS, monkey flower, a genus of 
the didynamia angiospermia class of plants, 
with double stigmata, and a ringent mono- 
petalous flower; the fruit is a bilocular cap- 
sule, with several seeds in each cell. There 
are three species. 
MIMUbOPS, a genus of the octandria mo- 
nogynia class of plants, the corolla of which 
consists of eight petals ; and its fruit is a 
drupe. There are three species, trees of the 
East Indies. 
MINA, in Grecian antiquity, a money of 
account, equal to a hundred drachms. 
MINE, a deep pit under ground, whence 
various kinds of minerals are dug out ; but 
the term is more particularly applied to those 
which yield metals. Where stones only are 
procured, the appellation of quarries is uni- 
versally bestowed upon the places from which 
they are dug out, however deep they may 
be. 
The internal parts of the earth, as far as 
they have been yet investigated, do not con- 
sist of one uniform substance, but of various 
strata or beds of substances, extremely dif- 
ferent in their appearances, specific gravities, 
and chemical qualities, from one another. 
Neither are these strata similar to one an- 
other, either in their nature or appearance, 
in different countries ; so that, even in the 
short extent of half a mile, the strata will be 
found quite different from what they are in 
another place. As little are they the same 
either in depth or solidity. Innumerable 
cracks and fissures, by the miners called 
lodes, are found in every one of them ; but 
these are so entirely different in size and 
shape, it is impossible to form any inference 
from their size in one place to that in another. 
In these lodes or fissures the metallic ore is 
met with ; and, considering the great uncer- 
tainty of the dimensions of the lodes, it is 
evident that the business of mining, which 
depends on that size, must in like manner be 
quite uncertain and precarious. 
The insides of the fissures are commonly 
coated over with a hard, crystalline, earthy 
substance or rind, which very often, in the 
breaking of hard ore, comes off along with 
it ; and is commonly called the capels or 
walls of the lode. 
Th* breadth of a lode is easily known by 
the distance betwixt the two irrerusted side* 
of the stones of ore ; and if a lode yields 
any kind of ore, it is a better sign that the 
walls are regular and smooth, or at least that 
one of them is so, than otherwise ; but there 
are not many of these fissures which have re- 
gular walls until they have been sunk down 
some fathoms. 
Thus the inner part of the fissure in which 
the ore lies is all the way bounded by two 
walls of stone, which are generally parallel 
to one another, and include the breadth of 
the vein or lode. Whatever angle of incli- 
nation some fissures make in the solid strata 
at their beginning, they generally continue to 
do the same all along, borne are very uncer- 
tain in their breadth, as they may be small at 
their upper part and wide underneath ; and 
vice versa. Their regular breadth, as well as 
their depth, is subject to great variation ; 
for though a fissure may be many fathoms 
wide in one particular place, yet a little far- 
ther east or west it may not perhaps be one 
inch wide. T his excessive variation happens 
generally in very compact strata, when the 
vein or fissure is squeezed, in a manner,, 
through hard rocks which seem to compress 
and straiten it. A true vein or fissure, how- 
ever, is never entirely obliterated, but always 
sitews a string of metallic ore, or of a veiny 
substance ; which often serves as a leader for 
the miners to follow, until it sometimes leads 
them to a large and richly impregnated part. 
Their length is, in a great measure, unli- 
mited, though not the space best fitted for 
yielding metal. The richest state for copper i 
is from 40 to 80 fathoms deep ; for tin, from 
20 to 60; and though a- great quality of 
either may be raised at 80 *or 100 fathoms, 
yet “ the quantity is often too much decayed 
and dry for metal.” 
The fissures or veins of the Cornish mines 
extend from E. to W. ; or, more properlv, 
one end of the fissure points W. and by S., or 
W . and by N., while the other trends E. and 
by S. or E. and by N. Thus they fre- 
quently pass through a considerable tract of 
country with very few variations in their di- 
rections, unless they are interrupted by some 
intervening cause. "But, besides this east and 
west direction, we are to consider what the 
miners call the underlying, or hade, of the 
vein or lode, viz. the deflection or deviation 
of the fissure from its perpendicular line, as it 
is followed in depth like the slope of the roof 
of a house, or the descent of the steep side of 
a hill. 'I’h is slope is generally to the north or 
south ; but varies much in different veins, or 
sometimes even in the same vein: for it will 
frequently slope or underlie a small space in 
different ways, as it may appear to be forced 
by hard strata on either side. Some of the 
fissures do not vary much from a perpendi- 
cular, while some deviate more than a fa- 
thom ; that is, for every fathom they descend 
in perpendicular height, they deviate like- 
wise as much to the south or north. Others 
differ so much from the perpendicular that 
they assume a position almost horizontal ; 
whence they are also called horizontal or flat 
lodes, and sometimes lode-plots. Another 
kind of these has an irregular position with 
regard to the rest, widening horizontally 
for a little way, and then descending perpen- 
dicularly almost like stairs, with only a small 
string or leader to follow after ; and thus they 
alternately vary, and yield ore in several fiat 
