T I N 



474 



T I \ 



taken off and put on a^nin in any position of the cylinder, | 

 the length of whi -h -li..,iM be equal to that of the K 

 lap* or bcnd. Longitudinal ruts, 

 the edge of a tin-plate, arc mail.- in the cylinder from the 

 circti: 'ivards the centre to any required depth or ; 



tan) mglc, as at b, t. nnd /." In order to make 



a right -angled Inp, such as is shown in the marginal figure 

 G, the c\ Under is turned into the position shown in tho 

 figure, with one of the radial cuts under the longitudinal 

 opening in the block a a ; the handles nre put on, and the 

 edge of the tin-plate g it inserted in the uppermost slit in 

 the cylinder. The handles are. then moved in the direction 

 indicated by the arrow and dotted lines, and the plate is 

 forced to assume the position of the dotted lines K', re- 

 ceiving at the some time the required lap or bend. By 

 returning the handles towards their original position, the 

 plate may be easily removed. If, in addition to the making 

 of the lap, the plate is to be bent so as to form a hollow 

 cylinder or tube, the motion of the handles is continued 

 until the cylinder is turned completely round, by which 

 means the plate will be wrapped or rolled round it. The 

 cavity in the block a a is made large enough to receive the 

 cylinder with this addition to its" thickness ; and if this 

 operation be intended, one side or cheek of the cavity is 

 made moveable on a pivot, so that it may be opened for 

 the purpose of lifting out the cylinder. The pipe is sub- 

 sequently removed from the cylinder by detaching the 

 handles and sliding it off longitudinally. Appended to the 

 description of this apparatus, In the Society's Transactions,' 

 is an account of a method of bending pipes of tin, copper, 

 or brass, by filling them with hard solder, and passing them 

 through two thick rings of the same substance, one of 

 which is fixed in a vice or work -bench, while the other is 

 attached to a handle of such length aato give the operator 

 sufficient leverage for bending the pipe in that portion 

 which intervenes between the rings. As the solder is 

 softer than the material of the pipe, the rings will give wa\ 

 to any dangerous pressure sooner than the pipe itseli'. 

 When the required curvature is obtained, the solder is 

 melted from the inside of the pipe. It is observed that in 

 performing this operation upon brass pipes, they should be 

 previously tinned on the inner surface, in order to - 

 a perfect union between the tube and the core of 

 solder. 



After a tin vessel has been rounded upon a block or 

 mandril, by striking it with a wooden mallet, and the 

 seams finished as above described, all its exterior edges are 

 sticngthened by bending a thick iron wire into the proper 

 form, applying it to what would otherwise be the raw 

 of the metal, and dexterously folding them over it 

 with a hammer. By this mean* the :i; of the 



articles is improved, and their durability and strength are 

 greatly increased. A superior kind of tin-ware, commonly 

 known as block-tin, is carefully finished by beating or 

 planishing with a polished steel hammer upon a metal 

 stake ; by which means the surface, which otherwise ap- 

 pears somewhat wavy, is made very smooth and silvery, 

 especially after it has been polished with dry whiting. It 

 is principally in the production of block-tin wares that 

 acaging ^ revolted to an a ready means of producing 

 grooved or ridged borders or other embossed ornaments. 

 This piocess consists in striking the metal between two 

 steel dies or swages, the facw of which bear the desired 

 pattern, and are made counterparts to each other. The 

 mouldings round the edges of dish-covers and other similar 

 articles are produced in this way: the swages embossing 

 the pattern in short lengths, and the article being gradually 

 turned round until every part of its circumference has been 

 (ubmitteil to their action. It was formerly usual to make 

 Mich mouldings separately for large articles, and to attach 

 them with solder; and Holland Mates that the practice ol 

 swaging them was introduced by Mr. King, a tinman in 

 Holburti, who executed very bold and handsome mould- 

 ings by placing the outside of the article upon a concave 

 bul or Ic ad, having a hollow line or groove sunk into it, 

 into which the rim of the cover or vessel was forced by 

 the application of a huge hammer on the inner side, until 

 the required degree of projection was obtained. The 

 border wa, then completed by the application of swages. 

 1 iibed. The lower die is usually fixed in 



an apparatus to which moveable guides are attached to in- 

 sure the -ion i.t the article to be operated on, 

 and the upper is made in the form of a hammer, the handle 





aud 



; tin 



of which is pivoted no as t i-ely 



the right p' - ap- 



.'iply working the \i\ ag.'-lmm- 



iner itself; but in 



mer is struck with a mallet. Very rni 1 . 1 

 articles are produced by enit . 

 in the same manner 



press or other machinery. Many cheap 

 manufactured at Birmingham in this way; and t 

 similar articles lire s. 



panned. A very beautiful method of orname 

 wares by producing a crystallized appearance on the sur- 

 face was much practised a few years since, under the name 

 o(rnoirf>' metattimu, < rd tin-pi 



in applying diluted nitro-mnriatic acid to the surfs > 

 the plate while slightly heated, and then with 



water, and covering witn a lacquer varnish, without which 

 the lustre of the crystalline appearance is speedily lost by 

 the action of the air. Dr. t're observes that -it would 

 seem that the acid merely lays bare the crystalline rt 

 ture really present on ever)' sheet, but masked by a film of 

 redundant tin ;' and he gives the following directions for 

 performing the process : The tin-plate, slightly heai- 

 to be placed over a tub of water, and to have it 

 rubbed with a sponge dipped in a liquor composed <>; 

 parts of aquafortis and two of distilled water, holding one 

 part of common salt or sal-ammoniac in solution. V 

 the crystalline spangles appear to be thoroughly brought 

 out, the plate should be immersed in water, washed wiih a 

 feather or a little cotton taking care not to rub so hard as 

 to disturb the crystallized film of tin which constitutes the 

 feathered surface , dried with a gentle heat, and imme- 

 diately coated with lacquer. If the whole surface be 

 plunged at once in cold water, but parti it by 



sprinkling cold water upon it, the crystallization will be 

 variegated with large and small figures. Similar i. 

 will be obtained." he ailds, by blowing cold air through a. 

 pipe ou the tinned surface, while it is jusi pa 

 the fused to the solid state; or a variety of <! 

 may be traced by playing over the surface of the plate 

 with the pointed flame of a blow -pipe.' '. IHrt. nf Arl/t, 

 p. KM and pp. li">.f, r_'5l.< By using col 

 very beautiful boxes and other ornamental >v be 



produced by this process. 



nri" i'f Tin Allni/x. Rritnnnin M'tul. Tin 

 forms the principal ingredient in various kinds of j 

 and other white metallic alloys, which are manufactured 

 into domestic utensils by cast ; 



n which much ingem Hand 



gives ail interesting account of the manufacture of tea- 

 pots and similar articles of Britannia metal, which 111 

 briefly noticed here. This manufacture was comm. 

 on a large scale at Sheffield, where it is still carried on, 

 about the year 177*1. by two individuals of the nan 

 Jessop and Hancock ; nnd the brilliancy, lightness, and 

 cheapness of the wares, which, when well made, greatly 

 resemble silver, have secured for them a 

 sale in this and other countries. The extreme facility 

 with which such allot shape 



leads however to the manufacture of many articles of so 

 flimsy a character that they speedily lose their form nnd 

 beauty. Various authorities differ gn the com- 



position of Britannia metal, but the proportions given by 

 Holland are SJcwts. of the best block- -tin, 2S Ibs. of mar- 

 tial regulus of antimony, S Ibs. of copper, and 8 1! 

 brass. The tin isfirst melted and raised to a red heat in a 

 stout cast-iron pot, and then the antimony, copper, and 

 brass are successively poured into it from the crucibles in 

 which they have been melted ; the mass being stirred 

 during the operation, to complete the mixture. The fusion 

 i by the continued application of fire under 

 the pot, the metal is removed by ladles to cast-iron boxes 

 or moulds, in which it is cast 'into slabs fifteen inches 

 Jong, six inches wide, and one inch thick ; or if for cast- 

 ing small articles, into smaller moulds to form it into con- 

 The thick slabs of metal are then ex- 

 tended bypassing them betwi 'Hers 

 until they are reduced to the r> mity. 

 This operation is performed without any annealing or 

 softening; and the edge< of tht me a little shat- 



( racked by it. 



Although most article's manufactured in silver are also 

 produced in Britannia metal, and in other alloys of sirailw 



