1854.] 



AUSTRIAN IMPERIAL PRINTING OFFICE. 



181 



taken for a similar purpose. None who participated in it suffered 

 from the climate or the accidental casualties of a journey. We 

 travelled under the powerful and in eveiy way efficient protection 

 of the Viceroy. We had an explicit and written permission to 

 make excavations, wherever we should consider it desirable, and 

 ■we employed it, to acquire a number of interesting monuments 

 for the Royal Museum at Berlin, which would either have remained 

 in Egypt as rubbish under the sand hills, or exposed, like so many 

 others, to be destroyed for all kinds of material purposes. 

 (To be continued.) 



The Austrian Imperial Printing Omce> : 



The Imperial Printing Office of Austria has exhibited the whole 

 collection of the new applications of the typographical art, such 

 as the galvanoplastic process, galvanography, galvanoglyphy, and 

 chemitypy, which, bringing their co-operation to the aid of typo- 

 graph}', enable it to reproduce, in some degree, nature itself. It 

 may, therefore, be said that these new branches are to typography 

 what photography is to the art of drawing. 



.The Galvanoplastic Process. — We have, for instance, seen 

 antediluvian fishes reproduced upon paper, at this exhibition, with 

 the exactness of nature itself. By means of successive layers of 

 gutta percha applied to the stone inclosing the petrified fish, a 

 mould is obtained, which, being afterwards submitted to the action 

 of a galvanic battery, is quickly covered with coatings of copper, 

 forming a plate upon which all the marks of the fish are repro- 

 duced in relief, and which, when printed at the typographic press, 

 gives a result upon the paper identical with the object itself. M. 

 Hulot, a mechanist and chemist attached to the mint of Paris, has 

 exhibited some sheets, each of them containing three hundred heads 

 intended for postage stamps, which are impressed at one stroke 

 from a plate of brass of a single piece, containing these three hun- 

 dred figures in relief. By a peculiar process, M. Hulot succeeds 

 in identically reproducing, without the least contraction, the origi- 

 nal engraving, which is on steel, but which might be engraved on 

 any other metal, or even on wood. It is by this same process 

 that M. Hulot has reproduced, for the Bank of France, the notes 

 engraved in relief in such perfection by French artists. 



Galvanography. — The Austrian Printing Office has shown 

 us some remarkable results of this process. An artist covers a 

 plate of silvered copper with different coats of a paint composed 

 of any oxide, such as that of iron, burnt terra sienna, or black 

 lead, ground with linseed oil. The substance of these coats is of 

 necessity thick or thin, according to the intensity given to the lights 

 and shades. The plate is then submitted to the action of the 

 galvanic battery, from which another plate is obtained, reproduc- 

 ing an intaglio copy, with all the uneveness of the original paint- 

 ing. This is an actual copper-plate, resembling an aquatint, and 

 obtained without the assistance of the engraver. 



Galvanoglyphy. — The experiments in galvanoglyphy are no 

 less interesting. Upon a plate of zinc, coated with varnish, a 

 drawing is etched ; then, with a small composition roller, a coat 

 of ink is spread upon this varnish, and left to dry. The ink is 

 deposited only on those parts where the varnish has not been 

 broken through by the graver, and leaves the sunken portion of 

 • the engraving free. When the first layer is dry, a second is ap- 

 plied, then a third, and so on, until it is considered that the origi- 

 nal hollows are deep enough. The plate thus prepared is placed 

 in the galvanic battery, and another plate is the result, on which 

 all the hollows of the engraving are reproduced in relief. This 



* Reports of the Juries of trie Great Exhibition. 



relief is more or less raised, according to the number and thick- 

 ness of the coats of ink successively applied. The process was in- 

 vented in Englandand patented by Mr. Palmer, of Newgate Street. 

 Chemitypy. — For the purpose of obtaining casts in relief from 

 an engraving, the process of chemitypy is equally ingenious. A 

 polished zinc plate is covered with an etching ground ; the design 

 is etched with a point, and bitten in with diluted aquafortis ; the 

 etching ground is then removed, and every particle of the acid 

 well cleaned off. For this purpose, the hollows of the engraving 

 are first washed with olive oil, then with water, and afterwards 

 wiped, so that there may not remain the least trace of the acid. 

 The plate, on which must be placed filings of fusible metal, is then 

 heated by means of a spirit-lamp, or any convenient means, until 

 the fusible metal has filled up all the engraving; and when cold, 

 it is scraped down to the level of the zinc plate, in such a manner 

 that none of it remains except that which has entered into the hol- 

 low parts of the engraving. The plate of zinc, to which the fusi- 

 ble metal has become united, is then submitted to the action of a 

 weak solution of muriatic acid, and as of these two metals the one 

 is negative and the other positive, the zinc alone is eaten away by 

 the acid, and the fusible metal which had entered into the hollows 

 of the engraving is left in relief, and may then be printed from by 

 means of the typographic press. 



Paneiconography. — This is a new process, invented by M. 

 Gillot, of Paris, and consists of a method of reproducing, by means 

 of the typographic press, any lithographic, autographic, or typo- 

 graphic proof, any drawing with crayon or stump, or any engrav- 

 ing upon wood or copper. Upon a plate of zinc, polished by 

 means of pummice-stone, the artist executes the required design 

 with lithographic crayon or ink, or transfers impressions from 

 lithography, wood engraving, or copper plates. The surface is 

 then inked over with a roller, so as to increase the thickness of the 

 ink, which is afterwards consolidated by dusting finely-powdered 

 rosin over the plate by means of a pad of wadding; the rosin 

 adheres only to the ink, and is readily removed from the other 

 parts of the plate. Afterwards, for the purpose of obtaining a 

 relief block, the plate is placed on the bottom of a shallow trough, 

 containing very dilute sulphuric or hydrochloric acid. By means 

 of a rocking motion given to the box, which, for that purpose, is 

 fastened to an axis, the acid is caused to pass slowly and continu- 

 ously to and fro over the surface of the plate. After the lapse of 

 half an hour, if it be a crayon drawing, the etching is completed, 

 and a relief block is obtained, in which it is only necessary to re- 

 move the large whites by saw-piercing. In case, however, of the 

 plate containing written matter, or many very fine lines, it is 

 necessary to withdraw it from time to time, and again ink the 

 surface with lithographic ink, and dust the powdered rosin, so 

 that the edges may be protected as much as possible from the 

 undermining action of the acid. These operations must be re- 

 peated until the necessary depth is obtained. Transfers may be 

 made from very old impressions of wood engravings, by sponging 

 them several times at the back with acidulated water, and then 

 operating as is usual with lithographic transfers. 



Atmospherical Electricity* 



BY PROFESSOR JOSEPH LOVERING, OF HARVARD UNIVERSITY. 



Continued from page 159. 



The third general division of this article proposes to inquire how- 

 it is that the earth becomes charged with electricity. I begin this 

 inquiry by observing that there are three dynamical processes, 

 very general and very efficacious, which aregoingonat all times 



