517 



DICYAXUM. 



DIE-SINKING. 



1732 and 1747, Zedler's ' Grosses vollstandiges Universal Lexicon aller 

 Wissenschaften und Kiinste,' &c., was published at Leipzig, in 52 TO!S. 

 folio. In 1751, appeared in Paris the first volume of the celebrated 

 ' Encyclopedic, or Dictionnaire Raisonn^ des Sciences, des Arts, et des 

 Metiers,' of Diderot and D'Alembert ; the 17th and last of the original 

 series was published in 1765, 11 vols. of plates being added to the text, 

 of which the first was published in 1762, the last in 1772. A Supple- 

 ment was afterwards added, consisting of four vols. of text and one of 

 plates, foL, 1776-7 ; and there is besides a 'Table Analytique' of the 

 whole work, compiled by M. Mouchon, in 2 vols. folio, Paris and 

 Amsterdam, 1780. Editions of the work have also been printed in 

 France and other parts of the Continent, both in quarto and octavo. 

 [DIDEROT, in Bioo. Div.] It has been followed in France by another 

 dictionary of arts and sciences of still greater extent, the ' Encyclopedic 

 Me'thodique,' begun in 1782 and finished in 1832, in 201 vols. 4to., 

 including 47 vols.. of plates. In this last-mentioned work every art or 

 science is treated of in a separate volume, or series of volumes ; so that 

 the whole is in fact merely a collection of dictionaries. Of other 

 foreign encyclopaedias, we may notice the German ' Conversations 

 Lezikon ' (as it was originally entitled), projected by Mr. Brockhaus, 

 the bookseller of Leipzig, and first published there in 1812. A ninth 

 edition of this work, enlarged to 15 vols. 8vo., was completed in 1848, 

 under its altered title of ' Allgeineine Deutsche Real-Encyclopadie fiir 

 die gebildeten Stande Conversations-Lexikon ; ' and a tenth edition is 

 now (1859) in course of publication. An edition of this work appeared 

 at Leipzig in 1852-58, of which we have already noticed the English 

 translations and appropriations. The French have also issued an 

 ' Encyclopedic des Gens de Monde,' in 22 vols. 8vo, Paris, 1833-44 ; an 

 ' Encyclopedic Moderne,' with its Supplement, in 86 vols. 8vo, Paris, 

 1855 57 ; a ' Dictionnaire de la Conversation et de la Lecture" (edited 

 by W. Duckett), in 68 vols., Paris, 1839-51; of which a new edition, 

 commenced hi 1851, is still in progress ; and a ' Conversations Lexicon,' 

 founded on the German, now in progress, in 8vo, Paris. There is also now 

 in course of publication the great work conducted by Professors Ersch 

 and Gruber [ERSCH, in Biou. Div.], entitled ' Allgemeine Encyclopadie 

 der Wissenschaften und Kiinste,' which began to be published at Leip- 

 zig, in 181 8, and of which 122 vols. 4to, have already appeared ; namely, 

 the portion from A to Gihom, in 66 vols. ; that from H to Juniua, in 

 31 vols ; and that from O to Phyxios, in 25 vols. There are other 

 German Cyclopsedias ; among the most noticeable are Meyer's ' Grosse 

 Conversations Lexikon fur die gebildeteu Stande,' in 38 vola royal 

 8vo, Hildburghausen, 1840-52, with a Supplement in vols., 1853-55, 

 and 8 vols. of plates, consisting of portraits, views, maps, charts, &c. ; 

 Pierer's ' Universal Lexikon der Gegenwart und Vergangenheit, oder 

 neuestes encyclopadischea Worterbuch der Wissenschaften, Kiinste, 

 und Gewerbe,' third edition, in 34 vola. 8vo., Altenburg, 1840-46. 

 ' Dent/who Enclycopiidie ; oder, Allgemeines Real- Worterbuch aller 

 Kiinste und Wissenschaften.' Von einer Gesellschaft Gelehrten (only 

 carried to letter K), 28 vols. 4to, Frank! am Mayn, 1778-1807; 

 ' Oeaterreichische National-Encyklopudie .... vorziiglich der neuern 

 und neueoten Zeit,' 6 vols. 8vo, Wien, 1835-37 ; being part of a series 

 with ' Oesterreichiaches naturhistorisches Bilder-Con venations- Lexikon,' 

 9 vols. 8vo, Wien, 1835-39 ; ' Conversatioiw-Lexikou der neuesten Lit- 

 teratur-Volker und Staatengeschichte,' 2 vols., Leipz. 1841-45 : and 

 Herzog'u ' Encyclopadie fiir Protestautische Theologie und Kirche,' to 

 which many eminent German divines have contributed, ill 10 vols. 

 8vo, 1853-9. A translation of a portion of this has also been published 

 in America. In Spanish, there was commenced in 1842 an ' Enciclopedia 

 Eapafiola,' in 8vo., published at Madrid, which is still in progress. At 

 Turin, a ' Nuova enciclopedia popolare Italiana,' begun in 4to.,iu 1856, 

 IB also in progress ; as is likewise the ' Svenskt Konversations-Lexikon,' 

 in 4 vols. 8vo., Stockholm, 1845-51. 



Some account of the encyclopedias in various languages, but neither 

 very clearly nor very accurately drawn up, and mixed with a great 

 deal of superfluous and useless matter, may be found in a little book 

 called ' Nouveau Systeme Bibliographique mis en usage pour la con- 

 naisance des Encyclopediee,' lie., 12mo., Paris, 1821. 

 DICYANUM. [MELLON.] 



DIDYMIUM (Di) is a metal recently discovered in cerite. Cerite 

 eventually yields, by treatment with sulphuric acid, large red crystals, 

 which are sulphate of didymium : when potash ia added to a solution 

 of this salt, hydrated oxide of didymium is precipitated ; it has a bluish j 

 violet colour, and during washing it absorbs carbonic acid from the air, 

 and when dried it consists mostly of carbonate of didymium and is of a 

 light reddish violet colour ; by exposure to a red heat the carbonic ' 

 acid is expelled, and the oxide is obtained in small lumps of a brown 

 or blackish colour ; the powder is light brown : if this oxide be ex- : 

 posed to a white heat it assumes a dirty grayish green colour. It has j 

 no alkaline reaction, and is dissolved pretty readily even by dilute 

 acids, which yield salts of an amethystine red colour ; the latter are 

 not p'recipitated by sulphide of ammonium unless heated ; the oxide is 

 insoluble in carbonate of ammonia. 



Before the blowpipe, the oxide mixed with microcosmic salt becomes 

 amethystine red with a tint of violet ; when heated with carbonate of 

 soda* on platinum foil, it melts into a grayish white mass. It does not 

 appear to have been reduced to the metallic state. 



DIELECTRIC. A term applied to a substance through or across 

 which the electric force is acting. [ELECTRICITY.] 



DIE-SINKING. In the preparation of coined money and of 

 medals, the most important feature is the engraving of the die 

 which is to form the stamp. The piece of steel is prepared with the 

 utmost care, and is brought to a soft state when about to be submitted 

 to the hands of the engraver. If the die or stamp be for a medal such 

 as those which have been executed at the Mint by Pistrucci and Wyon, 

 and of which the relief is great, the metal requires to be cut away to a 

 greater depth than in the dies intended for the coining of money, such 

 as shillings, &c. By very minute touches, and by the aid of small, fine, 

 hardened steel tools, the engraver cuts away the steel until he has 

 produced, in cavity or "intaglio," an exact reverse of the design for the 

 medal or coin. The steel, in a soft state while being engraved, requires 

 hardening before being applied to use. The face of the die is covered 

 with a protecting layer of pounded charcoal mixed with oil, and the die 

 is then placed face downwards in a crucible, where it is surrounded 

 with pounded charcoal ; after being heated to a cherry-red temperature, 

 it is taken out by means of tongs, and plunged into cold water, the 

 sudden action of which renders the steel extremely hard. When 

 further prepared, so as to be rendered more durable, it obtains the 

 name of the matrix, and might be used in that state to stamp coins or 

 medals ; but as such a matrix is very costly, and might be spoiled by 

 fracture, arrangements are made for producing multiplied copies of it. 

 A small block of soft steel is, by immense pressure, made to receive an 

 impress, in relief, from this matrix ; and from this second piece, which 

 obtains the name of the puncheon, after being hardened and re-touched 

 by the graver, dies or duplications of the original matrix are produced. 

 These dies, when intended for coinage, are intrusted to the Clerk of 

 the Irons at the Mint, whose duty it is to superintend the die-press 

 rooms, the purchasing and forging of the steel, and the engraving and 

 hardening of the dies ; to receive and transmit all orders respecting 

 the dies ; to be present whenever the die-press is used for multiplying 

 the dies ; and to_exercise general control over all matters relating to 

 them. 



In the use of dies by means of the stamping-press, the number of 

 blows required to transfer the device to a blank piece of metal depends 

 upon the depth of the intaglio. Professor Brande states, that in a medal 

 executed by Mr. Wyon, for the Royal Naval College, there was a repre- 

 sentation of the head of William IV., in such bold relief as to 

 require thirty blows of a very powerful press to complete the impres- 

 sion ; and that it was necessary, on account of the hardening produced 

 by the pressure, to anneal each medal after every third blow ; so that 

 every medal was placed in the furnace ten times during the process of 

 stamping. In another instance (a large medal struck by Boulton), 

 some of the copies are said to have received three hundred blows each, 

 and to have required heating and annealing after each blow. 



A remarkable method is sometimes adopted of producing medals 

 from a die by means of stamping, but upon metal which is in a semi- 

 liquid instead of a cold and solid state : the method is called en die/if", 

 and has been much practised in France. The metal of which these 

 iiii'd:ils are formed is one of the various kinds of fusible metal, such 

 :n will melt at a low temperature. Type-metal, consisting of five parts 

 of lead to one of antimony, will answer, for the purpose, but it is 

 deemed better when a little more lead is added to it ; many different 

 alloys of tin, lead, bismuth, and antimony, however, will suffice. The 

 die to be employed is fixed face downward at the lower end of a 

 stamper, which works within a box or case to prevent the liquid metal 

 from splashing about ; at the bottom of the box is a cast-iron plate, on 

 which is placed a small paper tray. The alloy is melted, and allowed 

 to cool down to a pasty state ; a little of it is placed in the paper tray ; 

 the box is closed on all sides, and the stamper is allowed to fall on the 

 alloy, by which a medallion is produced from the die, rough at the 

 edges, and with an impress only on one side. The contact of the cold 

 die solidifies the alloy, and produces a clear and tolerably sharp 

 impression. The medallions so produced are trimmed at the edge by 

 a lathe, and rendered smooth at the back ; sometimes two are fixed 

 together back to back, to form a perfect medallion ; and sometimes 

 they are mounted in cases, with only one side visible the surface 

 being bronzed with metallic sulphates. In some instances, instead of 

 cliche* medals being produced from engraved dies, cliche 1 moulds are 

 produced from models made of plaster, wood, sulphur, clay, wax, or 

 metal : thus, the Italian figure-casters often make casts from medallions 

 and small bassi-rilievi by means of moulds which have been made 



lit from models. 



Die-sinking is regarded in the above paragraphs chiefly in its con- 

 nection with the fine arts ; but the slightest glance at the industry of 

 Birmingham, and other seats of the metal manufacture, will show how 

 largely die-sinking is necessary for the operations carried on in the 

 stamping-works. In this point of view, a suggestion worthy of notice 

 was made by Mr. Kidd, of Sheffield, and communicated to the 

 ' Mechanics' Magazine ' in 1858. It was to the effect that die-sinking 

 might possibly be accomplished by the aid of electro-metallurgy. 

 " Take, as an example," he said, " a pair of dies for casting metal 

 buttons. Let a model in wax be made, with the face of the button 

 standing out in relief on a flat surface of (say) an inch all round its 

 edge. The face of the model must now have a conducting surface 

 imparted to it, either by black-ltad or by the phoephorxis and gold 

 solutitn. Then place it in an electiotyping apparatus for receiving a 

 coating of iron. AY hen this coating is of tolerable thickness (say one- 



