FLU

457

FLU

remains in what is left behind, which readily attracts moisture in acool place. 2. Soda, when put upon charcoal, melts superfi-cially, penetrates the charcoal with a crackling noise, and thendisappears. In the spoon it yields a permanent and pellucid sphe-ricle, as long as it is kept fluid by the blue apex of the flames, butwhen the heat is diminished, it becomes opaque, and assumes amilky colour. It attacks several earthy matters, particularly thoseof the siliceous kind, but cannot be employed on charcoal. 3.Crystallized borax, exposed to the flame urged by the blow-pipeor charcoal, first becomes opaque, white, and excessively swelled,with various protuberances, or branches proceeding out from it.When the water is expelled, it easily collects itself into a mass,which, when well fused, yields a transparent sphericle, retaining itstransparency even after cooling. If calcined borax be employed,the clear sphericle is obtained the sooner. Having provided everything necessary, the following directions, are next to be atlendedto. 1. A common tallow candle, not too thick, is generally pre-ferable to a wax candle, or to a lamp. The snuff must not be cuttoo short, as the wick should bend towards the object. 2. Theweaker exterior flame must first be directed upon the objext, un-til its effects are discovered ; after which the interior flame musthe applied. 3. We must observe with attention whether the mat-ter decrepitates, splits, swells, vegetates, boils, &c. 4. The pieceexposed to tlie flame should scarcely ever exceed the size of apepper-corn, but ought always to be large enough to be taken upby the forceps. 5. A small piece should be added separately toeach of the fluxes; concerning which it must be observed whetherit dissolves wholly or only in part; whether this is elfected withor without effervescence, quickly or slowly ; whether the massls . divided into a powder, or gradually and externally corroded ;with what colour the glass is tinged, and whether it becomesopaque, or remains pellucid. Having given these directions, Mr.Bergman proceeds next to consider the subjects proper to be ex-amined by the blowpipe. These he divides into four classes: 1.haline; 2. Earthy; 3. Inflammable; and 4. Metallic. Thesesubjects are treated at considerable length, in Mr. Bergman’sWritings, to which we refer the reader. Fixed alkalies, nitre,borax, tartar, and common salt, are the saline matters of w hichfluxes are generally composed. . But the word flux is more par-ticularly applied to mixtures of different proportions of only nitrea5 'd tartar; and these fluxes are called by particular names, ac-cording to the proportions of these ingredients, as in the following

Flux, White, is made with equal parts of nitre and of tartardetonated together, by which they are alkalised. The residuum. '■''is detonation is an alkali composed of the alkalies of the*"tre and of the tartar, both which are absolutely of the same’•ature. As the proportion of nitre in this mixture is more than

is sufficient to consume entirely all the inflammable matter ofthe tartar, the alkali remaining after the detonation is perfectlywhite, and is therefore called white flux ; and as this alkali is madevery quickly, it is also called extemporaneous alkali. When asmall quantity only of white flux is made, as a few ounces for in-stance, some nitre always remains undecomposed, and a little ofthe acid of the tartar, wTiich gives a red, or even a black colour,to some part of the flux; but this does not happen when a largequantity of white flux is made, because then the heat is muchgreater. This small quantity of undecomposed nitre and tartarwhich remains in white flux is not hurtful in most of the metallicfusions in which this flux is employed: but if the flux is re-quired perfectly pure, it might easily be disengaged from thoseextraneous matters by a long and strong calcination, withoutfusion.

Fi.ux, Crude. By crude flux is meant the mixture of nitre andtartar in any proportions, without detonation. Thus the mixtureof equal parts of the two salts used in the preparation of the whiteflux, or the mixture of one part of nitre and two parts of tartar forthe preparation of the black flux, are each of them a crude fluxbefore detonation. It has also been called white flux, from itscolour; but this might occasion it to be confounded with thewhite flux above described. The name, therefore, of crude (lux ismore convenient. Crude flux is detonated and alkalised duringthe reductions and fusions in which it is employed ; and is thenchanged into white or black flux, according to the proportions ofwhich it is composed. This detonation produces good effects inthese fusions and reductions, if the swelling and extravasation of thedetonating matters are guarded against. Accordingly, crude fluxmay be employed successfully in many operations; as, for in-stance, in the ordinary operation for procuring the regulus of anti-mony.

Flux, Black. Black flux is produced from the mixture oftwo parts of tartar and one part of nitre detonated together. Asthe quantity of nitre which enters into the composition of thisflux is not sufficient to consume all the inflammable matter of thetartar, the alkali which remains after the detonation contains muchblack matter, of the nature of coal, and is therefore called blackflux. This flux is designedly so prepared, that it shall contain acertain quantity of inflammable matter; for it is thereby capable,not only of facilitating the fusion of metallic earths like the whiteflux, but also of reviving these metals. From this property it isalso called reducing flux; the black flux, therefore, or crudeflux made with such proportions of the ingredients as to be con-vertible into black flux, ought always to be used when it is re-quired that metallic matters are at once to be fused and reduced.See Fusion.

FLUXIONS.

History of Fluxions.

('•) The doctrine of Fluxions comprehends the arithmetic ando ■Jiysis of fluxions, and Fluents or flowing quantities. It consistsv 'principal parts, one called the direct, and the other the in-f r ' e method of fluxions ; the first of these being the same in ef-int *' ie differential calculus, and the last the same with the

f<? r ‘d ca '‘ idus of the foreign mathematicians.c - v 2 -) It lias been a matter of much dispute among mathemati-Uv* nS ’ " " as d le inventor of this method of calculation ; and

ha° °! ll,e nl0S I celebrated philosophers of the seventeenth century,ton 6 a ' 1 ' c 'aim to the honour of the discovery, viz. Sir Isaac New-> and Mr. Leibnitz. It appears however certain, that Sir Isaac bad" 1 "" l ' le d r:t inventor of the method of fluxions, that he ,Use c ” m Pi ( 'ted his discovery about the year 1069, and had made ,t ( , r „ 0 .’i'c nrethoil in his Compendium of Analysis and Quadra- jba\> i 0t Curves before that time. His attention seems even to iibeen directed to the subject before the vear 1605. But it ;|no. i0. ’ <1

was M. Leibnitz that first printed any thing relative to this branchof calculation ; for in 1684, he gave the rules of the method in theLeipsic Acts of that year, but without demonstrations. Thesehowever were soon found out by the two brothers John and JamesBernoulli , who applied the calculus with considerable success to anumber of difficult problems.

(3.) In 1687, Sir Isaac Newton ’s Principia was published, aW’ork w hich is almost wholly founded upon the same calculus. Thecommon opinion then was, that Newton and Leibnitz had eachinvented it about the same time ; and in confirmation of this opi-nion, it was observed, that neither of them made any mention .fthe other, and that though they agreed in the substance oi thething, yet they differed in their ways of conceiving it, calling it > ?different names, and using, each, a dillerent notation. Ilow; • r,foreign mathematicians having first learned the method by in -of M. Leibnitz’s publication, became accu-toined to look i: • ;ihim as the sole, or principal inventor, and w ere ever alter stn .prejudiced ia favour of his notation, and mode of conceiving.

6 A ■ (4.) a