10 



THE POPULAR EDUOATOE. 



they are cut by the engraver upon blocks of box-wood such 

 blocks are not submitted to the press for printing from. A 

 certain number of copies might be so produced, but long before 

 the many thousands required were obtained the wood-block 

 would be worn out. To obviate this difficulty, the block, after 

 being engraved, is moulded in soft gutta-percha. This mould 

 is afterwards given a conducting surface by the means already 

 explained, and is then fit for metallic deposition by means of 

 the electric current. The thin shell] of copper so obtained is 

 afterwards backed up by type-metal, and fixed to a block of 

 mahogany, so that in dimensions, and in other respects, it is an 

 exact fac-simile of the original wood-block, with the exception 

 that its surface is hard enough to withstand the rough usage 

 of the press. 



Electro-plating is an art of no less importance than electro- 

 typing, and it is carried on in a similar way. The difference 

 between them is that in the former a layer of some superior 

 metal, usually gold or silver, is deposited on a foundation of 

 some baser material in such a way as to be permanently united 

 with it, while in the latter the layer of metal must be strong 

 enough to be separated from the mould. 



In electco-plating, too, it is the outer surface that has to be 

 seen ; the deposit must, therefore, be more even and polished ; 

 the operation is, however, very similar. The decomposing trough 

 must, of course, contain a solution of the metal to be precipi- 

 tated, and also a plate of it in order to maintain the strength. 

 Kg. 66 shows the usual arrangement of the apparatus. The 

 surface of the metal is nearly always dull wheii it leaves the 

 trough ; it is, however, scoured with a wire brush and after- 

 wards burnished, and is susceptible of a very high polish. 



With some metals it is found almost impossible to make 

 a deposit of silver adhere ; they are, therefore, coated with 

 copper first, and to this the silver adheres without difficulty. 

 The surface has, however, to be most carefully freed from all 

 grease or tarnish before being immersed in the decomposing 

 trough. The solution of silver usua-lly employed is made by 

 dissolving cyanide of silver in a weak solution of cyanide of 

 potassium. 



Etching may also be done by means of the electric current. 

 The surface of the copper plate is coated in the usual way with 

 wax, and the design traced on it so as to remove the wax from 

 the lines. It is then connected with the positive pole of the 

 battery, and the copper is eaten away from the exposed places in 

 a more even and regular way than it would be by an acid. 



It may be mentioned hero that some of these chemical 

 effects may be produced to a limited extent by means of a cur- 

 rent of frictional electricity. If we take a piece of blotting- 

 paper, and, having moistened it with a solution of iodide of 

 potassium and starch, lay on it a piece of wire connected with 

 the prime conductor, and near to this another connected with 

 the rubber or the ground, iodine will be evolved at the former, 

 and its presence shown by a blue stain 

 on the paper. 



Another plan of showing these effects 

 is to tako two triangular pieces of paper 

 (Fig. 67) one, A, coloured blue by 

 litmus, the other B, coloured with tur- 

 meric and moisten both with a solution of sulphate of soda, 

 having laid them on a piece of glass. Now hold A to a point, p, 

 fixed in the conductor ; in a little time it will turn red, thus indi- 

 cating the presence of free acid, while B will turn brown from 

 the alkali set free. 



LESSONS IN GERMAN. LXIL 



73. AUXILIARIES OF THE SECOND CLASS. 

 {!.) THE second class of auxiliaries embraces the following : 



Fig. 67. 



3c(, mag, I am allowed (may). 

 3d) ttiUI, I will (purpose). 

 3d; foil, I am obliged (shall). 

 3d; fanit. I am able (can). 



3d; tarf, I am permitted ; I 



dare. 



3d; mufi, I am obliged (must). 

 3d; laffe, I let. 



(2.) These verbs are, for the most part, very irregular in con- 

 jugation, and serve simply the purpose of modifying other 

 verbs with the ideas of liberty, possibility, or necessity, and the 

 verbs thus modified are required to be in the infinitive mood ; 

 thus, er mag ladjen, he may (has permission to) laugh ; id; faint 

 fd;mben, I can (am able to) write ; where Iad;en and fdjmben are 

 both in the infinitive, governed respectively bj mag and f ann. 



(3.) In the perfect and pluperfect tenses, however, the past 

 participle of those verbs is used only when the principal verb 

 is not expressed. Its place is supplied, in such cases, by thu 

 infinitive, the translation, of course, being the same in either 

 case ; as : 



3d; fyabe ifin feficn foiuien (instead of gefonnt), I have been 



able to see him. 

 Sr I;at ttMvtnt miiffcn (instead of gemupt), ho was obliged to 



wait. 

 QJJan ftatte ubct ifin lacfycn mogcn (instead of gemocfyt), one 



might have laughed at him. 

 drr at tcm iSefd)(e nid;t gct)ord;en toofien (instead of gciuuflt) 



he has not been willing to obey the command. 

 Scl, I;abe fcin @cl;eimmji nriffcn tiirfcn (instead of getuvft), I 



have been allowed to know his secret. 

 <te Bitten eS tfyun follcn (instead of gefcllt), they ought to 



have done it. 



@ie fyii&cit tint gefycn laffen (instead of gelaffen), they have suf- 

 fered him to go. 



For a full display of the forms of the verbs, and for further 

 remarks on their uses, see the Section on the Mixed Conjugation 

 ( 83). 



The verb laffen (to let) does not belong to the Mixed conjuga- 

 tion. This verb is used either in permitting or commanding ; 

 as, id; I;abe tf)n gcfyen laffen, I have allowed him to go ; id, fya&e u)n 

 f ommcn laffcn, I have ordered him to come ; which two meaningr, 

 are near akin. When used with a reciprocal pronoun, it has it* 

 equivalent in such phrases as can, is to, ought to, may ; as, bciS 

 lafit fid; nicfyt tf;un, that cannot be done ; literally, does not allow 

 itself to be done. The infinitive active after fafjen must often 

 be translated passively. 



74. CONJUGATION OF VERBS. 



(1.) There are two conjugations of verbs . the Old and the 

 New. The difference between them lies mainly in the mode o- 

 forming the imperfect tense and the perfect participle. 



(2.) The verbs of the Old form are commonly denominated 

 Irregular Verbs. But as nearly all the primitive verbs in thu 

 language are conjugated in this way, and few, except the deri- 

 vative verbs (now the larger class), ever assume the other form, 

 it is the custom of the best German grammarians to adopt the 

 classification which we have given. This will occasion no con- 

 fusion or inconvenience to those who prefer the common classi- 

 fication ; since it is only necessary to remember that the things 

 are the same, though the names have been changed. 



(3.) In order to afford the ready means of comparing the ter- 

 minational differences between the Old and New forms of con- 

 jugation, we subjoin the following tabular view of the simplr 

 tenses and participles, in which alone differences of this kind 

 can exist. 



(4.) In the compound tenses, the auxiliary alone being sub- 

 jected to terminational variation, the mode of inflecting thes*- 

 tenses becomes of course perfectly uniform in all classes of 

 verbs. Hence, to secure a complete acquaintance with the forms 

 of the compound tenses, little more is necessary than a bare 

 inspection of the paradigms. 



75. TERMINATIONS OF THE SIMPLE TENSES. 

 Old Conjugation. New Conjugation. 



