Ft" NX El,. 



ITl'X \r r 



ID like manner may the equililirium of the rafters in a curb-roof be 

 determined. [Roor.] 



l-TNM'.I.,a hollow conical vessel with a small tube issuing from 

 iU ]-x ; it is an instrument much used in common and doni. 

 for conveying fluid* into vessels of small apertures, and in chcmi. ,! 

 operation* it it vised not only fur tliis purpose but for the important 

 one of filtering. [Kn.rn.vi n>\. | Kor the mere purpose of the transfer 

 from one vewel to another of such fluids a* do not act upon metals, 

 funnels are commonly made of copper, pewter, or tin plate, and thin 

 is especially the case when they are employed for conveying ]..>,.,!,?- 

 into bottle*. When, however, they ore employed by the chemist with 

 acid, alkaline, or such other solutions as dissolve or corrode the 

 metals, then funnels are made of earthen or stone ware, or of glass. 

 When iud for nitration, especially in smaller and nicer operations, 

 those of glass are always to be preferred. 



Fl'KFl KAMIDE (C-H^N.O.). A product of the action of 

 ammonia U|x>n furfural. It is isoineric with furf urine. 



Kt/UHTKINK, a substance artificially formed by Mr. Fownes, 

 possessing the projierties of a vegetable a'.kaloiil. ami forming salts 

 with acids. It in procured by boiling furfuramlilr with solution of 

 caustic potash. 1 U formula is C^H^N^O,. 



I-V ItKl'UOL (C 1(( H.O,). When sugar or starch in nctod upon with 

 a mixture of dilute sulphuric m-i.l ami ]>eroxide of manganese, t : 

 produced in addition to formic acid, a peculiar oily matter which lias 

 been named furfural. It is produced by the following reaction : 



( 'ni.i. + . = 2CO, + C,,H,0 4 + OHO 



- : '.. 



Fnrfurol. 



The same Ixxly IMII also be obtained by other reactions. Furfurol is 

 nn oily lluicl, almost colourless at first, but on exposure to nir, it 

 gradually becomes brown, and finally black. It boils at 330 Fahr., 

 and is easily soluble in water and in alcohol. Left in contact with 

 ammonia for several hours, it in completely converted into a yellow 

 semi-crystalline mass of furfuramide. 



FUUIKS. | KIMENIDES.] 



FURLONG. [WEIGHTS AXD MEASURES.] 



FURNACE. The common grate is the most familiar example of a 

 furnace. It is constructed of iron, and of various forms. The fuel is 

 kept in it only by bare, in order to throw the heat out into the room. 

 Indeed this is its principal use; aud although its heat is barely 

 sufficient to melt thin plate silver, yet many chemical operations may 

 be performed in the common stove, and its flat sides or cheeks furnish 

 a lower degree of heat, by which evaporation and digestion may be 

 effected. The term furnace is, however, usually applied only to the 

 fire-places used in manufacturing oiHirations, such as those of chemists, 

 metallurgy, and civil engineering. 



For the smaller operation* in chemistry a great variety of furnaces 

 have been invented. The annexed figure represents one of these, a 



Wind Furnace. 



INat Furnncc. 



rind fvrnaft : in this a very high temperature is produced without 

 the use of bellows, by means of a powerful draught. The chimney <>f 

 a wind furnace should bo narrow and high ; the furnace, represented 

 as connected with and projecting from tin- chimney, .-h.,nl,l I,,- of such 

 height as to allow the operator to look into it ; it should be from 12 

 to 15 inches square, and furnished with moveable bars and a cover ; 

 every part exposed to the fire should be constructed of the best fire- 

 resisting bricks. In the figure a crucible is represented as placed in 

 the furnace, and its cover is on. This furnace is much employed in 

 the reduction of metals, and in the assaying of copper and various 

 other ores. The fuel used is either coke, a mixture of coke and 

 charcoal, or anthracite. Another kind is the chemical Uatt -furnace. 

 The exterior consists of a blue pot eighteen indies in height and 

 thirteen inclu-x in external diameter at the top. A small blue pot, of 

 even and a half inches internal diameter at the top, has the lower 

 part cut off, so as to leave an aperture of five inches. This, when ] .t 



into the larger pot, rests upon ita lower external edge, the tops of UK 

 two being level. The interval between Uu>m, which gradually 

 increases from tin- lower to the upper part," filled with pulverised 

 glass-blowers' |>ots, to which water enough has been added to moisten 

 the powder, which is pressed down by stick*, so as to make the whole 

 a compact mass. A round grate is then dropped into the furnace, of 

 such a size that it rests an inch above the lower edge of the inner pot : 

 the space beneath it therefore constitutes the air-chamber, am) (lie 

 part above it the body of the furnace. A horizontal hole, conical in 

 form, and 14 inch in diameter on the ester Lronyli the 



outer pot, forming an opening into the air-chamber at the lower |rt, 

 its use being to receive the nozzle of the bellows. The fuel em: 

 is coke, and the furnace is used with a pair of double bellows mounted 

 on on iron frame : the furnace being raised upon an iron stool so as to 

 bring the aperture of the air-chamber to a level with the nozzle 

 of the bellows. Such a furnace as this is sufficiently powerful 

 to melt pure iron in a crucible in 12 or 15 minutes. It will 

 ^effect the fusion of rhodium, and even pieces of pun- platinum 

 have sunk (<>; HUT into one button in a o ''il by it; 



all kinds of crucibles, inelmlin h an<l tin- Hessian, 



soften, I'll ;c, ami become frothy in it. Mr. I'.ii.nl.n I 

 an this lung in u-e at the K'l.yal Institution. 



The uaai/ or cupelliny furnace is a small furnace made of iron, liueil 

 with lire-proof clay, and containing a muffle ; it is used principally for 



tho cupellation of gold and silver, which is placed upon a cupel in tin- 

 inutile, previously heated to redness. The interior of the furnace con- 

 tains merely the muffle resting upon two bars of iron ; it is put about 

 two-thirds into the furnace, and there is consequently left a space 



i it ami the Kick part of the furnace. In the annexed cut, 

 a is the orifice of the muffle, which may be closed by iron 

 placed at the side. The opening 6, placed below the grate, and pro- 

 vided with slides, serves as well as tho upper opening c to regulate 

 the draught. Charcoal is used in this furnace. 



Recently gas furnaces for the analysis of organic substances, ami for 

 the fusion of metals, have been ingeniously contrived : the first by Dr. 

 Hofmann, and the latter by Mr. (Jii'lin. The first will bo found 

 described ill the ' Quarterly Journal of Hie Chemical Society,' vol. xi.. 

 p. 30, and the second in the ' Chemical News," No. 3. Kr metallurgic 

 operations on the large scale, as well as in making alkalies, re.l lead, 4c.. 



fberutiiry furnace is much uwd. This is shown in the ai. 

 figure. A is the space furnished with a grate or bars, to contain the 



Rcvcrbcrtlorr Fornnce. 



combustible, which ia cither coke, coal, or wood, according to circum- 

 stances; B B F i. the part on which tho flame acts, E F is tho roof, li c 



