want of room, to another opportunity.

making borax out of calcined tar tar, fal ammoniac, and allum, i not an irrational one, and that the

Hints for the making of Borax. Borax is a falt that deserves the

confideration of chemical enquirers, because it is of mechanical ufe, particularly in foldering, and as fuch, the feveral mechanics that manufacture metalline utenfils have occafion for it.

The borax now used in Europe is all prepared or refined from the tinkal that is brought from the Eaft Indies; but Dr. Lindolff in his Chemistry, lately published in Germany, is of opinion, that it might be made in Europe without the aid or affiftance of tinkal, or any other ingredient brought from Afia; and for his reafons he gives the com, pound parts of borax, as they appeared to him in his analisation, and recommends to the enquiring chemift to feparate and examine every part of this falt, and by this means the knowledge of making the fame might be obtained; as his method of analifing borax is no other than what is commonly known in chemistry, I will not trouble your readers with it, but only relate the hints he gives for making the fame.

As borax is the most perfect neutral falt, with fome other contents intimately united, he thinks it might be done, and a borax produced by the helps of allum, foap, and a strong alcaline lye; and from his experiments he believes, that Paracelfus's procefs of

vantageoufly used to the fame pur pose.

Upon the whole, I apprehend Dr. Lindolff is very well acquaint ed with the nature of borax, and I doubt not but a borax may be made after his method; but then I think it would be too expenfive, and not fuperfede the importation of tinkal from Afia; yet I believe

it may be made here to advantage; but the method I would recom

mend should be this, viz. (1) the four or acid water that comes out of coal mines; (2) train-oil, or any other fifh-oil, or, indeed, any fat that could be had cheap; and (3) the strongest alcali of kelp, and all thefe ingredients to be worked in a liquid ftate till they are well mixed and chriftalize like anfwer all the ends of borax. a falt, which falt, I believe, will

I am, &c. D. W. LINDEN

pofe, has added the following reflection; "If this be true, we have here a discovery of the longitude under all the variations of climes, feafons, weather, &c. an invention which the great Leibnitz and Bernouilli thought as impoffible as the fquaring of the circle, or the difcovery of an univerfal panacea." Now, Sir, whether the information contained in the above article be true or falfe, or whether fuch a discovery be practicable or only chimerical, certain it is, we fhould be no otherwise benefited by it, in regard to the longitude, than as it might be productive of a time- keeper, that would not want winding up. It is, however, an equable as well as a conftant motion, that is wanted to determine the longitude; fo that every fuch machine must be regulated by a pendulum, and would then, as well as in other refpects, be fubject to the variations, of climes and feafons. Again, the reflector is mistaken in faying, that both Leibnitz and Bernouilli thought this difcovery impoffible. The former, indeed, conftantly affirms its impoffibility; and yet in his difputes with Papin, published in the Acta Lipfienfia, he declares, that if the force of a body in motion be in a direct proportion to its velocity (as it is now univerfally known to be) a perpetual motion must be poffible. And with regard to Bernouilli, you may find in the first volume of his works, page 41, feq. that he not only declares it to be poffible, but alfo

that he had actually conceived a method whereby it might be rendered practicable. De la Hire and other eminent mathematicians pretend, indeed, to have demonftrated the abfolute impoflibility of fuch a difcovery. But it is certain that others have not thought thofe der monftrations applicable to all poffible machines. Among these may be mentioned the late profeffor 'S Gravefande of Leyden, undoubtedly one of the first mathematicians, and as well verfed in geometry and mechanics as any man of his time. Yet this gentleman wrote a treatife profeffedly to prove the poffibility in queftion nay, it appears that he went fo far as to think it had been actually discovered in the machine of Orfyreus, that made such a noise at Heffe Caffel about forty years ago; and which he examined at the defire of the landgrave, with the utmost care and attention. Indeed, I cannot help thinking that the difpute fubfifting between the philofophers concerning the momenta of moving bodies, which was at that time at its higheft warmth, prevented that machine from being fo much attended to as it deserved. In this opinion alfo I am strongly confirmed by a letter, written by that profeffor to Sir Ifaac Newton on the fubject of that machine; which letter, as I know not where it is to be found in the English language, I have translated from the French, for the information or entertainment of your readers.

A letter

to Sir Ifaac Newton, concerning Orffreus's awheel.

SIR,

Doctor Defaguliers has doubtless fhewn you the letter that baron Fischer wrote to him fome time ago, about the wheel of Orfyreus ; which the inventor affirms to be a perpetual motion. The landgrave, who is a lover of the fciences and fine arts, and neglects no opportunity to encourage the feveral difcoveries and improvements that are prefented him, was defirous of having this machine made known to the world, for the fake of public utility. To this end he engaged me to examine it; withing that, if it should be found to anfwer the pretensions of the inventor, it might be made known to perfons of greater abilities, who might deduce from it thofe fervices which were naturally to be expected from fo fingular an invention. You will not be difpleafed, I prefume, with a circumftantial account of this examination; I tranfmit you therefore a detail of the moft particular circumftances obfervable on an exterior view of a machine, concerning which the fentiments of moft people are greatly divided, while almost all the mathematicians are against it. The majority maintain the impoffibility of a perpetual motion, and hence it is that fo little attention hath been paid to Orfyreus and his invention.

For my part, however, though I confefs my abilities inferior to thofe of many who have given their demonstrations of this impoffibility; yet I will communicate to you the real fentiments with which

this machine. It is now more than seven years fince I conceived I difcovered the paralogifm of thofe demonftrations, in that, though true in themfelves, they were not applicable to all poffible machines; and have ever fince remained perfectly perfuaded, it might be demonftrated that a perpetual motion involved no contradiction; it appearing to me that Leibnitz was wrong in laying down the impoffibility of the perpetual motion as an axiom. Notwithstanding this perfuafion, however, I was far from believing Orfyreus capable of making fuch a discovery; looking upon it as an invention not to be made (if ever) till after many other previous difcoveries. fince I have examined the machine, it is impofiible for me to express my furprise.

But

The inventor has a turn for mechanics, but is far from being a profound mathematician, and yet his machine hath fomething in it prodigioufly aftonishing, even tho' it fhould be an impofition. The following is a defcription of the external part of the machine, the infide of which the inventor will not permit to be feen, left any one fhould rob him of his fecret. It is an hollow wheel, or kind of drum, about fourteen inches thick, and twelve feet diameter; being very light, as it confifts of feveral crofs pieces of wood framed together; the whole of which is covered over with canvas, to prevent the infide from being feen. Through the center of this wheel or drum runs an axis of about fix inches diameter, terminated at both ends by iron axes of about three quarters of an inch diameter, upon which

the machine turns. I have examined these axes, and am firmly perfuaded that nothing from without the wheel in the leaft contributes to its motion. When I turned it but gently, it always ftood fill as foon as I took away my hand; but when I gave it any tolerable degree of velocity, I was always obliged to stop it again by force; for when I let it go, it acquired in two or three turns its greateft velocity, after which it revolved for twenty-five to twentyfix times in a minute. This motion it preserved fome time ago for two months, in an apartment of the castle: the doors and windows of which were locked and fealed, fo that there was no poffibility of fraud. At the expiration of that term indeed his ferene highnefs ordered the apartment to be opened, and the machine to be stopped, left, as it was only a model, the parts might fuffer by fo much agitation. The landgrave being himfelf prefent on my examination of this machine, I took the liberty to afk him, as he had feen the infide of it, whether after being in motion for a certain time, no alteration was made in the component parts; or whether none of those parts might be fufpected of concealing fome fraud: on which his ferene highness affured me to the contrary, and that the machine was very fimple.

You fee, Sir, I have not had any abfolute demonftration, that the principle of motion, which is certainly within the wheel, is really a principle of perpetual motion; but at the fame time it cannot be denied me that I have received very good reafons to think fo, which is a ftrong prefumption in

VOL. VI.

favour of the inventor. The landgrave hath made Orfyreus a very handfome prefent, to be let into the fecret of the machine, under an engagement nevertheless not to difcover, or make any ufe of it, before the inventor may procure a fufficient reward for making his. difcovery public.

I am very fenfible, Sir, that it is in England only the arts and fciences are fo generoufly cultivated as to afford any prospect of the inventor's acquiring a reward adequate to this difcovery. He requires nothing more than the affurance of having it paid him in cafe his machine is found to be really a perpetual motion; and as he defires nothing more than this affurance till the conftruction of the machine be displayed and fairly examined, it cannot be expected he fhould fubmit to fuch examination before fuch affurance be given him. Now, Sir, as it would conduce to public utility, as well as to the advancement of fcience, to discover the reality or the fraud of this invention, I conceived the relation of the above circumftances could not fail of being acceptable. I am, &c.