COACH-MAKINC 



TAR. 



used, and the name " axle " is given to it Formerly the axle was made 

 t<> r. v.'Ke \\itli the wheels, but now the wheels are generally made to 

 revolve on and not with the axle. There are three part* iu the axle, 

 the two " arm*," which pan into the. naves of the two wheels, and the 

 " bed " or central part, which connects the two arms. The adj i 

 at the nave or centre of the wheel requires very careful management ; 

 and it is to this point that Collingc's " patent axle " ehieily relates. In 

 earlier modes of construction a ring wax put within the hollow of the 

 nare, and the end of the arm of the axle worked within this ring, an 

 arrangement which was intended to prevent the too rapid wear of the 

 wood by the friction of the axle. In the present practice, however, the 

 axles are fitted with iron boxes adjusted to the arms. To lessen 

 the friction arising from the two surfaces working together, black lead, 

 soap, grease, or ou is used ; and it is portly on account of the inge- 

 nious way in which this lubrication with oil is effected, that Collinge's 

 ' ' patent axle " is so much employed. Besides the mechanism for con- 

 necting the axle with the wheel, there is contained a little cup for 

 holding oil ; and as the wheel rolls along, this oil is pumped or drawn 

 nut of its receptacle, and made to lubricate the adjacent surface. 



In a well-finished coach, the Iratherin;/ and the /altttiny are among 

 the more important processes after the wood and iron work are com- 

 pleted. The former of these is somewhat remarkable. In the common 

 kinds of vehicles the wood and iron arc coated with paint laid on to a 

 considerable thickness; but for the better kinds, leather U applied to 

 the roof, and the upper part of the back, front, and sides, previous to 

 the process of painting; this is done chiefly to shield the wood-work 

 from the alternations of heat and rain. A singular example is here 

 shown of the pliability of leather ; for one hide, without seam, knot, or 

 joining, is made to cover the whole. " The hide, which is of a large 

 size and sound quality, is first thoroughly moistened and thrown over 

 the top of the coach, the edges hanging down on all sides. The currier 

 then rubs or presses it down all over the roof, until it lies close and 

 even in every jvirt. He next proceeds to one of the sides, and in like 

 manner rubs and scrapes the leather till all irregularities disappear. 

 The leather is in that soft and pliable state that it will yield to the 

 movement of the tools, and enable the workman to fit it to every part 

 of the coach with perfect closeness. A little consideration must show 

 that a superfluous fold of leather will occur at each corner ; yet by 

 working it towards a central point at the back or front, the currier 

 succeeds in erasing or pressing out all irregularities, and in producing a 

 surface sufficiently flat and smooth for the subsequent operations of 

 the painter. The division between the upper and lower portions of a 

 coach is usually covered by beading of some kind or other, and the 

 leather is trimmed or cut to this line of division." (' Penny Magazine,' 

 -'5.) Any cut or crack in the leather, however small, would In- 

 fatal to the success of this remarkable mode of covering coaches. 



A coach receives a far thicker coating of paint than the wood -work 

 of a house, since it could not else admit of the very high polish to 

 which it owes so much of its beauty. The principal plain surfaces, 

 such as the door? and panels, receive ten, twelve, or even fifteen 

 distinct coatings, each one thoroughly dried before the next is applied ; 

 and at intermediate times all the roughnesses derived from the |..iim 

 are smoothed down by pumice-stone, rotten-stone, and other like sub- 

 stances. The leathered top, in the best coaches, sometimes receives 

 as many as twenty-five coatings of paint. The paint, which is formed 

 from nearly the same materials as that used for house-painting. 

 namely, mineral colours, linseed-oil, and turpentine, is of a white 

 colour for the earlier coats, a yellowish tint for those next applied, and 

 depends for its tint in the later coatings on the taste of the maker. All 

 time several coatings being dried and smoothed, the surfaces receive 

 ax or eight applications of copal varnish ; and it is the subsequent 

 polishing of this varnish which imparts the smooth, lustrous, and 

 beautiful appearance to the panels and plain surfaces. 



Mr. Hooper, a practical coach-builder, in a paper recently read before 

 the Society of Arts, drew attention to several interesting matters con- 

 nected with his art Of these, we will notice three, relating to the 

 rlOT of work-people employed in coach-making, the kinds of lace and 

 xilk required in finishing a carriage, and certain desiderata among 

 coach-builder*. On the first point he said : " Carriage-workmen are 

 divided into separate classes and trades. There are tody-matrn, who 

 form and make the part in which the persons sit; carriage-mat-' >-., who 

 make the under works, apply the parts necessary for backing or turning 

 the carriage, fix the axles and springs, Ac,; vkttUn or MMfarbMl ; 

 jvinm, who make the glass-frames, blinds, boxes, trunks, Ac. ; Jitttrt, 

 who fit and suspend the bodies on the under works, and apply tin; 

 various parts furnished by special manufacturers, such as lamps, 

 handles, Ac.; bnrly and carriuyr painlrrt; trimmer*, who fit up the 

 inside* of carriages, and fix the silks, cloth, and laces in the necessary 

 parts; Imlhrr-tforlm, divided into cultm, incen, tral-trimmm, and 

 Aonuw-BuUxn, according to the different works they an engaged 1 1 1 >n ; 

 trnitkt, divided into carriage tmitiu, tody-tmithi, tyrc-tmitht, and tjmny- 

 imitiu ; victmen, who chisel and file the iron-work made by the mnitlis ; 

 earetn; mcycr*; j>n/M<n,wb.i> produce the brilliant ]<olish on carriage 

 panels ; ktrald painteri ; cantrt, usually women, who interlace the neat 

 cane-work now so fashionable on carriage panels ; and linen, women 

 who sew together the cloth, silk, lace, Ac., after being cut out by the 

 trimmers." Concerning the silk and lace used in coach-making, Mr. 

 Hooper said : " Formerly a kind of silk called lutestring was in use. 



This was superseded in England by a strong ribbed silk called tabaret 

 After a time, this tabaret was copied in France, where the manu- 

 facturers considerably improved it l.y overcoming a difficulty, and pro- 

 ducing a figure on the surface. This, in its turn, was copied in I 

 (about 1848), with much success, and has now almost superseded all 

 other kinds for carriages ; it is called re/a in France, and 6oinir 

 England. The improvement in this kind of silk goods has been so 

 rapid in England for several years past as to have overtake- 

 fabricanto, with a good chance of surpassing them in quality at . 

 price. Carriage laces appear to have been made for many years in this 

 country of a quality far superior to the foreign laces; they [the 

 foreigners] have, however, now succeeded in making them of ex. 

 quality. The Germans have been introducing a considerable quantity 

 of good lace into this country for some months past, at a very reduced 

 price compared to English-mode laces; this however will ju-olably 

 he soon counteracted, as it has caused some enterprising manufacturers 

 in Coventry to establish improved looms for this department of weaving, 

 oiid to produce goods of equal quality at somewhat lower prices." 

 Mr. Hooper's remarks on desiderata were to the following effect: " \Ve 

 ore in want of several improved materials and appliances to facilitate 

 the manufacture of carriages. Among the former, are, colourless oils 

 for painters' use ; a colourless varnish (all the copal varnishes now in 

 use having a brown tinge, which is injurious to delicate colours) ; a 

 durable ultramarine blue ; and cheaper and more durable lakes. 

 Among the latter [class of desiderata], is a machine for sewing 

 for carriages and harness : though various attempts have been made, 

 they have up to the present time been unsuccessful, as they will not 

 work with a strong waxed thread, or draw the stitches sufficiently tight. 

 A machinist producing such a machine at a reasonable price wi t i i 

 a large demand for them; seeing that, besides the great quantity of 

 leather-sewing required for carriages and carriage-harness, saddlery, army 

 accoutrements, and military harness would lay claim to its assistance.' 



COAGULATION, the solidification of a liquid produced without 

 evaporation and without crystallisation. It is also often effected with- 

 out reducing the temperature of the substance coagulated, in whieh it 

 differs from mere congelation. 



Coagulation occurs in various ways in different fluids. Thus v. In -i 

 albumen, or the white of egg, is heated, it is rendered 

 coagulates. The spontaneous coagulation of the blood, by whieh it i* 

 resolved into serum and coagulum has already been noticed. [BLOOD, 

 NAT. HIST. Drv.] The cause of the coagulation of casein by tin 

 of rennet on milk, is as yet unexplained. Acids induce the curdling of 

 milk by neutralising the alkali by which the casein is held in solution. 



There ore some cases of pure chemical action which resemble 

 coagulation in appearance ; when, for example, solutions of snip! 

 soda and nitrate of lime are mixed, a sudden solidification taker 

 but this is a case of confused crystallisation, and not of coagulation. 



COAL TAR. When coal is heated in close vessels [GAS, MAM 

 FACTURE OF) a large quantity of gas is evolved, from whieh on cooling 

 there separates out a dark coloured, badly smelling, treacle-like sub- 

 stance, called coal-tar. It possesses very considerable interest from 

 the fact, that by distillation it furnishes a number of compounds now 

 almost indispensable in the arts and manufactures. For this purpose 

 large quantities of it are heated in immense iron stills. The portion* 

 that first distil over, constitute, when rectified, coal-naphtha, so im- 

 portant as a solvent of india-rubber and gutta-percha. The second 

 port ion of the distillate, about 30 per cent, is technically known as 

 ntary naphtha, coal oil, or dead oil : it is used as a lubricating 

 and on account of its antiseptic properties is employed to p> 

 timber ; thus railway sleepers soaked in it resist the action of air ami 

 moisture for a for greater length of time than usual. Coal-oil is also 

 largely used for burning into the lampblack with whieh print. -iV ink is 

 made. The residue in the retort, after the naphtha and coal-oil are 

 entirely volatilised is pitch, used in forming asphalte pavements, and in 

 the manufacture of block japan for varnishing iron work. 



Coal-tar mixed with the c-oal dust formerly wasted in mining 

 tions forms an excellent artificial fuel ; it is usually rendered d 

 and portable by being pressed into the form of square blocks. 



Finally, colouring matters and perfumes may be obtained from coul- 

 ter, though at present not in all cases economically. 



Naphtha, coal-oil, and pitch, are each of them mixtures of several 

 definite chemical compounds, and by careful rectification, Ac., m.iy li 

 separated from each other. They are usually divHi <l into three classes, 

 basic, acid, and neutral. The following is a list of those that have. 

 been examined : 



i: .i -. 

 Picolino. 

 Leucoline. 

 Aniline. 

 Pyridinc. 



Neutral substances : 



Acid-. 



Acetic. 

 Carbolic. 



Bninolic. 



Llqntd. 

 Benzole. 



Toluole. 



Gun. 

 Cymole. 



Solid. 

 Paraffin. 

 Naphthalin. 

 Paranaphthalin. 

 Pvren. 

 Cnrysen. 



