SIR,
Trange

Strange

as the following account may appear to every reader, it is nevertheless true; and if any perfon doubts the fact, after confidering the following relation, you may refer them to me, or any other of the gentlemen whofe names I have made known to you. for that purpose.

About fourteen years ago, a particular friend of mine who had a garden near James-ftreet, Bedfordrow, was informed by his fervant that a chrysanthemum (a flowering plant commonly known) in the garden, appeared to have very fmall particles of quickfilver fpread over the whole furface of its leaves and ftalks. My friend (who is not apt to let the flightest information efcape him, and by that means wants very little) examined this plant with all the attention due to fo extraordinary a production, and was thoroughly convinced of the fact; every leaf and ftalk had a multitude of fmall globules of quickfilver, adhering thereto, and which feemed to (and no doubt did) iffue from the perfpiratory ducts of the plant.

The fact being afcertained, my friend fuffered feveral ingenious

men of his acquaintance to examine the plant, and enquire into the caufe; who were all fatisfied of this extraordinary production, though none could account for it; and it remains a mystery to this day.

My friend, and other perfons who examined it, frequently collected a great part of the quickfilver from feveral of the branches by ftriking them, and catching the globules or small drops which inftantly united, into the hand, and left no doubt that it was pure crude quickfilver. And the next day, after thus gathering it, it gave fresh proofs of its limbetic quality; for not only the furface would be again powdered over, but in the hollow of the leaves, and particularly in those formed by the infertion of the footftalks, fmall drops alfo would be formed by the conflux of the small particles continually emitted.

In this ftate it continued about three weeks or a month, till the froft killed it, together with the rett of its fpecies.

My friend, knowing his fervant to be ingenious, took every precaution to find out whether he wa, tered the chryfanthemum with any folution of quickfilver, or ufed any art, or whether it really was the production of chance; and he was thoroughly convinced of the latter; for had the fervant known fuch a fecret, he could have repeated it another year, and thereby have raifed a large fum of money by expofing fuch a curiofity to the public,

The only tolerable reason, therefore, which can be affigned towards leading to a difcovery, is, that as my friend frequently amufed himself with a variety of chymica experiment

experiments (among which there were fome wherein quickfilver was employed in various forms) the refuse of it, together with the wafhings of the glaffes and crucibles used in thefe experiments, were thrown out near the place where this chryfanthemum grew, and the grateful plant undertook fpontaneously to restore again to its mafter in this unheard-of manner, and in purity too, what it had received in fome corrupt ftate. On the other hand, my friend made many experiments on the fame kind of plants, all which either died or failed of the wifhed for effect.

Perhaps this account may lead fome of your readers to purfue this matter further; many great difcoveries have been made by chance; but as this story borders on the marvellous, you are at liberty either to print or tell the name of,. Sir,

Your humble fervant,

Dec. 17, 1763. P.S. If, as I have heard afferted, it be true, that men who have taken calomel in great quantities, have with a microscope perceived it to iffue through the pores of the fkin, it cannot be more extraordinary than that a plant fhould be operated on in the fame manner.

PHILIP THICKNESSE.

History of a new Metal known by the name of White Gold or Platina; by Mess. Macquer and Baume. Extracted from the' Memoirs of the Academy of Sciences at Paris, for the year 1758, published last year.

the beginning of the prefent centu ry. This however is no proof that it was altogether unknown in for mer times, though it may be taken for granted that no ufe was made of it; and the great difficulty there ftill fubfifts of fluxing it, add to the probability of this opinion. How long foever it may be fince this metal was firft discovered, its properties are at this time but new truths, of which it is very likely that a confiderable number lie ftill concealed; and that those already found out might turn to advantage by being re-examined and confirmed by new experiments.

The firft who fearched into the nature of platina was Mr. Charles Wood, an English metallurgift; whofe operations on this fubject are recorded in the Philofophical Tranfactions for the year 1750; fince which time Mr. Scheffer and Dr. Lewis have directed their enquiries to the fame object. The refult of the trials of the former are printed in the Memoirs of the Academy of Sweden for the year 1751, and of the latter in the Philofophical Tranfactions for 1754. These are the principal works concerning this fubject, which appeared abroad before Mr. Macquer's, of which we shall here give an account: we fhould obferve, however, that Mr. Margraaf, has likewife read a memoir upon it to the academy of Berlin; but his researches were not made public before Mr. Macquer had completed his inquiries.

The platina on which Mr. Macquer made his experiments, has, like that which was examined by the other chemifts, the following characters; it is in fmall and pretty fmooth grains, moft of them refembling, as to their figure, pyrami

dal triangles with blunted points; their colour not much unlike that of course filings of unrufted iron, but approaching nearer to a filvery whiteness after being foaked in an acid, or heated to a high degree. Mr. Macquer fuppofes, with great probability, that the metal owes its name to the laft property, as derived from the word plata, which in Spanish fignifies filver.

The name of white gold, which has likewife been given to this metal, arifes out of certain properties which alfo belong to gold, fuch as to be nearly of the fame fpecific gravity as gold; to refift, like that, the action of fulphur, lead, antimony, the royal cement, and all pure acids; and to fubmit, like gold, to no folvent but aqua regalis, and hepar sulphuris.

None of the platina that has been hitherto examined is perfectly homogene. Gold is fometimes found in it, as in that which Mr. Macquer examined. The fubftance moft frequently met with among it, and in the greatest quantity, is a fmall black fand, brilliant and very pointed, which the load-ftone attracts as readily as iron.

In order to examine the ductility and other properties of platina, it was neceffary to procure an ingot of it of a proper fize; but the fuccefslefs attempts that had till then been made to flux it, left but little hopes of any fuch thing. True it is, that there might still be ways of increafing the activity of fire, beyond what the chemifts had yet been able to do, and this confideration determined Mr. Macquer to have recourse to new expedients. The wind-furnace and the forge had proved useless, though the fire had been kept up fifty hours,

A fire capable of fufing the mixtures of Mr. Pott, in his Lithogeognofy, and faid to have afforded him the hardest and the least brittle glafs, would not fufe platina, but only agglutinate its grains together. This experiment produced fome other phænomena, amongft which was one hitherto unobferved, viz. an actual increase of the weight of the platina on which the experiment was made, no lefs than fourteen grains to an ounce. This platina, thus increafed in weight, was fubjected to a fecond trial, which produced a fecond increafe; lefs indeed, but yet fenfible. The augmentation Mr. Macquer afcribes to a calcination of fome fubftance of a different nature from the platina, intermixed with it: for it is well known that there are fome fubftances, as vitriol, antimony, &c. whofe weight is increafed by calcination.

The platina was expofed to the heat of the glafs-houfes at Sevres for five days and nights together, without any other alteration of it than fuch as above-mentioned.

After fuch fort of trials, it was not to be expected to gain any new difcovery by means of fuch furnaces as are employed in chemical operations; but a thirst of knowledge animates the imagination, and furnishes contrivances. Mr. Macquer found the means of producing, in the forge of his own elaboratory, a heat far ftronger than what has been known to be done. To this end he added two large pair of double bellows, to that of the forge, and concentrated their action in one focus. This difpofition greatly increafed the heat: in lefs than an hour and a

quarter

quarter the lining of the furnace melted all down, and formed maffes of glafs which choaked the nofes of the bellows; the crucible was also vitrified, but the obftinate platina exhibited only fome grains perfectly round, as white as filver, which feemed to have undergone a perfect fufion yet a flight stroke of a hammer reduced them to powder.

After having in vain employed the feveral means we have recited, there still remained one which promised fome degree of hope, and the rather worth trying, as it had never been made ufe of by any chemist in the examination of platina; this was to expofe the platina to the focus of a good burning fpeculum.

The fpeculum Mr. Macquer ufed, was of glass, its diameter two and twenty inches, and the diftance of its focus twenty-eight inches. In half a minute it melted a gun-flint, and changed it into transparent glass; vitrified Heffian crucibles and fragments of glafs-house pots in three or four feconds; made forged iron fume, melt, boil, and turn to a vitrescent fcoria in an inftant; nay, melted the gypseous ftones, which Mr. Pott feems to regard as unfufible.

These effects, with several others, invited Mr. Macquer to fubmit platina to fuch an agent; he did fo, and here follows the refult.

The platina he ufed is that faid above to have been expofed to a glafs-house fire, and whofe grains were agglutinated together; as they were then in a folid mafs, they could be the more convenient ly expofed to the focus by holding

The platina thus exposed to the focus of the fpeculum, first turned to a blueish white, cafting off by fits very lively fparks, and diffuf ing a very fenfible fume; finally, in about a minute it was in a true. fufion; but with this particular, that the melted parts did not drop to the ground, but attached themfelves to thofe next the limits of the field of the focus.

Thofé melted parts fhone like filver, and their furface was rounded, bright, and polifhed. Being hammered on a small steel anvil, they were flatted to a thin plate without any cracking; in a word, they afforded fufficient marks of malleability, not only far beyond what they had before the fufion, but even fuch as gave hopes that they might be fpread as thin as the leaves of gold or filver.

Mr. Macquer having examined the properties which the action of fire difcovers in platina, fubmitted this metal to the action of other folvents. Of all the acid menftruums aqua regalis alone proved a folvent of platina, at least whilst it remained in its natural state.

This diffolution produces various phænomena. It requires a great quantity of aqua regalis, and is effected much more eafily by a

fand heat than without it.

Mr.

Macquer takes notice that the precipitates of platina made with volatile and fixed alkalis, have not

that

that red colour which Dr. Lewis attributes to them in general, except when no more of those alkalis is ufed than what is barely fufficient to faturate the acid; which obfervation led him to every natural explanation of the colour the precipitate affumes in the cafe we have been speaking of.

It has been long known in chemiftry, that precipitates always carry down along with them part of the diffolvent and of the precipitant: this truth, which is abundantly fenfible in the precipitate of platina, afforded Mr. Macquer the means of accounting for feve ral phænomena which Dr. Lewis had noticed in the precipitation of platina, though that learned chemift has not explained them.

The red precipitate of platina, mixed with a flux compofed of calcined borax, cream of tartar, and white glafs, after being expofed to a forge heat, produced a lump of the complexion of platina, with all the refemblance of a metal that had been well melted. Although this lump had not the fatif factory tokens of malleability, yet there is room to believe that the fufion had not been fufficiently perfect: this is a point which Mr. Macquer intends to examine hereafter, as alfo the vitrescent matter, into which the precipitate of platina was converted, after the operation of the fpeculum,

The cupellation of platina by lead is alfo one of the objects which have been examined by Dr. Lewis, and wherein Mr. Macquer propofed to furmount the difficulties which that ingenious gentleman feems to have met with this operation gave Mr. Macquer a re

fult which at firft feemed no more. fuccefsful than that of Dr. Lewis ; but a repeated examination opened to him very different properties; the platina, instead of increafing in weight, as Dr. Lewis had obferved, was found to have loft a fixteenth part; it was moreover very extenfible under the hammer. The fame platina cupelled, and then diffolved in aqua regalis, fhewed not the leaft marks of any remaining lead.

The whole of Mr. Macquer's obfervations, compared with what other chemists have delivered about this metal, feems to establish the following matters of fact. That platina is a third perfect metal, as fixed, as indeftructible, as unalterable as gold and filver; that it is not abfolutely unfufible; that there is even room to hope, that by mixing it with deftructible me. tals, and employing a fufficiently durable and intenfe heat, it may be fluxed in large furnaces. The attempts that have hitherto, or may be hereafter made with this view, cannot be too much applauded; it is easy to apprehend of how great utility in arts a metal may prove which refifts the action of air, water, fire, fulphur, acids, and the voracious metals, and had the ftrength and hardness of iron combined with all these qualities. Wife motives have determined the Spanish miniftry to interdict the working of their platina mines, and to prohibit the commerce of it; however, the lights that chemistry has already let us into concerning this metal, may make us eafy as to any abufes that may be made of it, and afford hopes, that it may in due time be

the