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Diamond. IAMOND, a genus of earths of the filiceous kind, black; but on closer examination appeared in some Diamond.

called Adamas Gemma by the Latins, Demant parts transparent, and in others charged with foulness,
by the Germans and Swedes, and Diamant by the on which the black hue depended.
French, is the hardest of all stones hitherto discovered; These gems are lamellated, confifting of very thin
commonly clear or transparent ; though this property plates like those of talc, but very closely united; the
may perhaps belong only to the crystals, and not to direction of which must be found out by lapidaries be-
the rock from which they originate. When brought fore they can work them properly: Such as have
to Europe in its rough state, it is either in the form of their foliated substance not in a Aat position, are called
roundish pebbles, with shining surfaces, or of octedral by the workmen diamonds of nature.
crystals; but though they generally appear in octa- The names of oriental and occidental, given by jewel.
dral forms, yet their cryftals are frequently irregular, lers to this and all other precious stones, have a differ-
especially when the surface inclines to crystallize du- ent meaning from the obvious sense ; the finest and
ring the shooting of the whole crystal, and also when hardest being always called oriental, whether they be
several of them unite in one group; in which case the produced in the eaft or not. Those called occidental
one hinders the other from assuming a regular form. are of inferior value ; but according to Mr Jefferies,
Mr Magellan, however, informs us, that diamonds who has written a treatise on the subject, the diamonds
sometimes assume other forms. He has seen a rough of Brasil equal the finest oriental ones. The art of
diamond in its native state, of a regular cubical form, cutting these gems was invented in 1476 by Louis de
with its angles truncated or cut off; likewise ano. Berquen a native of Bruges in the Austrian Nether-
ther belonging to Dr Combe of London, whose square lands. This stone becomes luminous in the dark, by
lides were naturally joined by two very narrow long fa- exposure during a certain time to the rays of the sun ;
cets, forming angles of about 120 degrees; and the by heating it in a crucible ; by plunging it in boiling
corners were quite perfect.

water; or by rubbing it with a piece of glass. By
Though the diamond is commonly clear and pellu- friction it acquires an electrical property, by which it
cid, yet some of them are met with of a rose colour, attracts the substance used for foils called black maslic,
or inchining to green, blue, or black, and some have and other light matters. The author of the Chemical
black specks. Tavernier saw one in the treasury of Dictionary says, that diamonds are refractory in the
the Mogul, with black specks in it, weighing about fire, and even apyrous. Nevertheless, experiments have
56 carats ; and he informs us, that yellow and black been made, which prove that diamonds are capable of
diamonds are produced in the mines at Carnatica. Mr being dislipated, not only by the collected heat of the
Dutens also relates, that he saw a black diamond at fun, but also by the heat of a furnace. Mr Boyle says,
Vienna in the collection of the prince de Lichten- that he perceived certain acrid and penetrating exha-
stein. Some diamonds have a greenish cruft; and of lations from diamonds exposed to fire. A diamond by
these M. l'avernier relates, that they burst into pieces exposure to a concave speculum, the diameter of which
while working into a proper shape, or in the very act was 40 inches, was reduced to an eighth part of ils Plilof.
of polishing on the wheel
. In confirmation of this, weight *. In the Giornale de Letterati d'Italia, tom.

Tranfire, he mentions a large diamond worth upwards of 5000l. viii. art. 9. we may read a relation of experiments

no 386. Sterling, which burst into nine pieces while polishing made on precious stones, by order of the grand duke on the wheel at Venice.

of Tuscany, with a burning lens, the diameter of which The finest diamonds are those of a complexion like was two thirds of a Florentine ell, near the focus of that of a drop of pure water. It is likewise a valuable pro- which was placed another finaller lens. By these experty if they are of a regular form and truly made; as periments we find, that diamonds were more altered by also that they be free from stains, spots, specks, flaws, folar heat than moit of the other precious stones, aland cross veins. If diamonds are tinctured yellow, though not the leait appearance of a commencing fublue, green, or red, in a high degree, they are next fion was observable.

A diamond weighing 30 grains, in elteem; but if they are tinctured with these colours thus expofed during 30 seconds, lost its colour, luftre, only in a low degree, the value of them is greatly di- and transparency, and became of an opaque white. In minished. There are also diamonds of other com- five minutes, bubbles appeared on its surface; soon afplexions ; such as brown, and those of a dark hue: terwards it burft into pieces, which were dislipated; the first resembling the browneft sugar-cardy, and the and the small fragment which remained was capable of latter dusky iron. In the Philosophical Commerce of being crushed into tine powder by the presure of the Arts, Dr Lewis tells us of a black diamond that he blade of a knife. Neither the addition of glafi, flints, himself had seen. At a distance, it looked uniformly fulphur, metals, or falt of tartar, prevented this difii. Vol. VI. Part I.




Diamond. pation of diamonds, or occafioned any degree of fulion. which this fubftance defends metals from destruction by Diamonl.

By this heat rubies were softened, and lost some of fire. He was confirmed in his opinion, by observing
their colour, but preserved their form and weight. By that diamonds were not preserved from the action of
addition of a third lens, a further degree of fusion was tire by surrounding them with powder of chalk and
given to rubies. Even then rubies could not be made of calcined hartlhorn, and including them in close ver-
to unite with glass. By having been exposed to this fels, so well as when the charcoal had been employed.
heat, the surface of the rubies which had suffered fu- Some chemists even thought that the perfect exclusion
fion, loft much of their original hardness, and were of air alone was sufficient to preserve diamonds, and
Dearly as foft as crystal. But their internal parts, doubted whether the balls and crucibles of porcelain
which had not been fused, retained their hardness. E- employed by M. D'Arcet had excluded the air with
meralds by this heat were rendered white, or of various sufficient accuracy. Indeed, in one of M. D'Arcet's
colours, and soon afterwards were fused. They were own experiments, a diamond included in a ball of por.
found to have loit part of their weight, and to be ren- celain had refitted the action of fire. In order to al.
dered less hard and brittle,

certain this question, M. Cadet exposed diamonds in Experiments were also made by order of the empe. covered and luted crucibles to the violent heat of a forge ror Francis I. on precious itones; from which we find, during two hours ; by which operation the diamonds that diamonds were entirely diffipated by having been loft only ifth part of their weight. He infers, that exposed in crucibles to a violent fire of a furnace du. the destruction of diamonds by fire in open vessels is ring 24 hours ; while rubies by the fame heat were not not a true volatilization ; but merely an exfoliation, altered in weight, colour, or polith. By expofing dia- caused by the fire expanding the air contained between monds during two hours only at a time, the following the thin plates of which these stones confit, and that alterations produced on them by fire were observed. by this exfoliation or decrepitation these plates are re. First, they loit their polish ; then they were split into duced to fo fine a powder as to escape observation. thin plates; and, lailly, totally diffipated. By the M. D'Arcet objected against the experiments of his fame fire, emeralds were fused. See Alagafin de Ham- adversaries, that they were not of sufficient duration to bourg, tom. xviii.

decide against his, which had lafted several days. He The action of fire on diamonds has, notwithstanding renewed and multiplied his experiments, which conthe above mentioned experiments, been lately doubted firmed him in his opinion of the volatilization of diain France; and the queition has been agitated by seve. monds in vessels perfectly closed ; and that this effect Tal eminent chemists with much interest, and numerous of fire on diamonds is not a mere exfoliation or mechaexperiments have been made which throw some light nical feparation of the plates of which these stones on the subject. M. D'Arcet found, not only that dia. confift, he infers from the parts of the diamonds permunds included in porcelain crucibles close, or covered vading the most folid porcelain crucibles without being with perforated lids, and exposed to the long and in- perceptible, and from the luminous appearance firit tense heat of a porcelain furnace, were perfectly diffi- noticed by M. Macquer, and which was afterwards obpated; but also, that these stones could in a few hours served by M. Roux to be an actual flame. be totally volatilised with a much inferior degree of Diamonds are found only in the East Indies, and in heat, by exposing them in a coppel, under the muffte Brasil in South America. The diamond mines are of an eslay-furnace. In this latter experiment, he ob- found only in the kingdoms of Golconda, Visapour, ferved that the diffipation was gradual, and that it was Bengal, and the island of Borneo. There are four effected by a kind of exfoliation. The dissipation of mines, or rather two mines and two rivers, whence •diamonds expofed in coppels was confirmed by M. Mac- diamonds are drawn. The mines are, 1. That of Raolquer ; who further oblerved, that the diamonds were, conda, in the province of Carnatica, five days journey before the dissipation began, rendered, by the fire, from Golconda, and eight from Visapour. It has been brilliant and shining, as it were, with a phosphoric discovered about 200 years. 2. That of Gani, or Coulight. In order to determine whether the diffipation lour, seven days journey from Golconda eastwardly. of diamonds was actually effected by their reduction It was discovered 140 years ago by a peasant, who diginto vapour, or by a combustion or other effect of air ging in the ground found a natural fiaginent of 25 caupon them, Meffrs Lavoitier, Macquer, and Cadet, ex- 3. That of Soumelpour, a large town in the pofed diamon's to intense heat in an earthen retort, kingdom of Bengal, near the Diamond-mine. This during several hours, but without any other effect than is the most ancient of them all : it hould rather be that their polish was destroyed, and about 4th of their called that of Goual, which is the name of the river, in weight diminished. M. Mitouard put diamonds in a the fand whereof these stones are found. Lastly, the tobacco-pipe filled with pounded charcoal and accu- fourth mine, or rather the second river, is that of SucTately closed with lute. He further fecured the dia- cudan, in the island of Borneo. monds from accefs of air or fame, by placing the to- Diamonn-Mine of Raolconda.- In the neighbourbacco-pipe in a crucible, to which another crucible was hood of this mine the earth is fandy, and full of rocks. inverted and carefully luted. The diamonds, thus fe- and copse. In these rocks are found several little cluded from external air, having been exposed to the veins of half and sometimes a whole inch broad, out most intense heat which could be excited in a well con- of which the miners, with a kind of hooked irons, fructed furnace, were not thereby altered or diminish- draw the sand or earth wherein the diamonds are ; ed. M. Mitouard was induced to believe, that the breaking the rocks when the vein terminates, that the charcoal conduced to the preservation of diamords not track may be found again, and continued. When a merely by excluding the air, but by some peculiar pro- fufficient quantity of earth or fand is drawn forth, they perty, which he supposes may be the same as that by wash it two or three times, to separate the itones there



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Diamond. from. The miners work quite naked, except for a round with stores, earth, and fascines, and lading ou: Diamnd. brany thin linen cloth before them; and belides this pre- the water, dig about two feet deep: the land thus gut

porod caution, have likewise inspectors, to prevent their con- is carried into a place walled round on the bank of the cealing of stones : which, however, maugre all this river. The rest is performed after the same mamer care, they frequently find means to do, by watching op- as at Coulour, and the workmen are watched with equal portunities when they are not observed, and swallow. ftriétners. ing them down.

Diamond-Mine in the island of Borneo, or river of
DIAMOND-Mine of Gani or Coulour. In this mine Succudan.- We are but little acquainted with this
are found a great number of stones from 10 to 40 ca. mine ; the queen who reigns in that part of the illaed
rats, and even more; and it was here that famous dia- not allowing itrangers to have diy conimerce in these
mund of Aureng-Zeb the Great Mogul, which before itones : though there are very fine ones to be bought
it was cut weighed 793 carats, was found. The at Batavia, brunight thither by Stealth. They were
fones of this mine are not very clear; their water is anciently imagined to be softer than those of the other
usually tinged with the quality of the foil; being black mines; but experience ihows they are in no respect in- .
where that is marshy, red where it partakes of red, ferior to them.
sometimes greeu and yellow, if the ground happen to Befide these four diamond-mines, there have been
be of those colours. Another defect of some conse- two others discovered ; one of them between Coulour
quence is a kind of greafiress appearing on the dia- and Raolcenda, and the other in the province of Car-
mond, when cut, which takes off part of its lustre. natica ; but they were both closed up almost as soon as
There are usually no less than 60,000 persons, men, discovered : that of Carnatica, because the water of
women, and children, at work in this mine.

the diamonds was always either black or yellow; and
When the miners have found a place where they in the other, on account of tireir cracking, and flying in
tend to dig, they level another fomewhat bigger in the pieces when cut and ground.
neighbourhood thereof, and inclose it with walls about The diamond, we have already observed, is the
two teet high, only leaving apertures from space to hardeit of all precious stones. It can only be cut and
space, to give passage to the water. After a few fu- ground by itself and its own subitance. "To bring it
pertiitious ceremonies, and a kind of feast which the to that perfection which zugments its price fo confia
maiter of the mine makes for the workmen, to encoll derably, they begin by rubbing several against each
rage them, every one goes to his business, the men other, while rough ; after having firit glued them to
digging the earth in the place first discovered, and the the ends of two wooden blocks, thick enough to be
woinen and children carrying it off into the other held in the hand. It is this powder thus rubbed off
walked round. They dig i 2 or 14 feet deep, and till the stones, and received in a little box for the purpote,
such time as they find water. Then they cease dig- that serves to grind and polith the stones.
ging; and the water thus found ferves to wash the Diamonds are cut and polished by ineans of a mill,
earth two or three times, after which it is let out at which turns a wheel of loft iron (prinkled over with
an aperture reserved for that end. This earth being diamond-duit mixed with oil of olives. The fame
well washed, and well dried, they fift it in a kind of duit, well ground, and diluted with water and vine-
open fieve, or riddle, much as we do corn in Europe ; gar, is used in the fawing of diamonds ; which is
then thrash it, and tift it afresh ; and lastly, search it performed with an irun or brass wie, as fine as a hair.
well with the hands to find the diamonds. They work Sometimes, in lieu of lawing the diamonds, they cleave
naked as in the mine of Raulconda, and are watched them, especially if there be any large ftuivers thercina
after the like manner by inspectors.

But the Europeans are nut usually daring or export e-
DIAMOND-Mine of Soumeipour, or river Goual. - nough to run the risk of cleaving, for fear of breaking.
Souincipour is a large town built all of earth, and co. The fict water in diamonds means the greatest pu-
vered with branches of cacao-trees : the river Goual rity and perfection of their complexion, which ought
Tuns by the foot thereof, in its passing from the high to be that of the purest water. When diamonds fall
mountains towards the south to the Ganges, where it short of this perfection, they are said to be of the fe-
lofes its name.
It is from this river that all our fine cond or third water, &c. till the stone



propera diamond points, or sparks, called natural sparks, are ly called a coloured one: for it would be an impropriery brought. They never begin to feek for diamonds in to speak of an imperfectly coloured diamond, or one this river till after the great rains are over, that is, af. that has other defects, as a itone of a bad water only. ter the month of December; and they usually even Mr Boyle has observed, from a person much conwait till the water is grown clear, which is not before versant in diamonds, that some of these


in their January. The season at hand, cight or ten thousand jough state, were much heavier than others of the same persons, of all ages and sexes, come out of Soumel- biguess, especially if they were cloudy or fvul; and pour and the neighbouring villages. The most expe. Mr Boyle mentions one that weighed 8 grains, which rienced among them search and examine the fand of being carefully weighed in water, proved to an equal the river, going up it from Soumelpour to the very bulk of that liquor as 2 to 1.

So that, as far as mountain whence it springs. A great fign that there could be judged by that experiment, a diamond weighs are diamonds in it, is the finding of those stones which not thrice as much as water : and yet, in his table of the Europeans call thunder-ftones. When all the sand specific gravities, that of a diamond is faid to be to of the river, which at that time is very low, has been water as 3400 to 1000; that is, as 3 to 1; and therewell examined, they proceed to take up that where. fore, according to these two accounts, there should be in they judge diamonds likely to be found ; which is some diamonds whose specific gravity differs nearly s done after the following manner : They dain the place from that of others. But this is a much greater dit.


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