NATURE-PRINTING 405 



taking copies of flat objects of nature and art in plates of metal by means of two steel 

 rollers. Here may be remarked the first real steps of the process from a simple con- 

 trivance to an art. The subsequent development which science has given to these 

 means, and the amplifications which experience has added, have realised what can 

 now be produced ; but it should not be assumed that adaptation and amplification are 

 invention. 



Various productions in silver of Kyhl's process were exposed in the Exhibition 

 of Industry held at Charlottenburg in May 1833. In a manuscript written by this 

 Danish goldsmith, entitled ' The Description (with forty-six plates) of the Method 

 to copy Flat Objects of Nature and Art,' dated May 1, 1833, is suggested the idea 

 of applying this invention to the advancement of science in general. The plates 

 accompanying this description represented printed copies of leaves, of linen and 

 woven stuffs, of laces, of feathers of birds, scales of fishes, and even of serpent-skins. 



It would appear that Peter Kyhl was no novice at the process. He distinctly 

 points out what he conceives to be its value by the subjects that he tried to copy, and 

 he enters into detail as to the precautions to be observed in the operation of impress- 

 ing metal plates so as to insure successful impressions. His manuscript explains that 

 he had experimented with plates of copper, zinc, tin, and lead. Still there existed 

 obstacles which prevented him from making any application of his invention. In the 

 case of zinc, tin, and copper plates, the plant, from the extreme hardness of the 

 metals, was too much distorted and crushed ; while in lead, though the impression 

 was as perfect as could be, there were no means of printing many copies, as it was 

 not possible, after the application of printer's ink, to retain the polished surface that 

 had been imparted to the leaden plate, or to cleanse it so thoroughly as to allow the 

 printer to take impressions free from dirty stains. This was a serious obstacle, which 

 was not compensated for even by the peculiarly rich surface of the parts that were 

 impressed, attributable to the lead being more granular than copper, the effect of 

 which is so favourable to adding density or body of colour, without obliterating the 

 veins and fibres. 



Peter Kyhl died in the same year that he made known his invention. At his 

 death his manuscripts and drawings were deposited in the archives of the Imperial 

 Academy of Copenhagen. 



To proceed to more modern efforts. Dr. Branson of Sheffield in 1847 commenced 

 a series of experiments, an interesting paper upon which was read before the Society 

 of Arts in 1851 ; and therein, for the first time, was suggested the application of that 

 second and most important element in Nature-printing, which is now its essential 

 feature the Electrotype. 



It then occurred to Dr. Branson that an electrotype copy would obviate the difficulty. 



He afterwards stated that he abandoned the process of electrotyping, in consequence 

 of his finding it tedious, troublesome, and costly to produce large plates. Having 

 occasion, however, to get an article cast in brass, he was astonished at the beautiful 

 manner in which the form of the model was reproduced in the metal. He determined, 

 therefore, to have a cast taken in brass from a gutta-percha mould of ferns, and was 

 much gratified to see the impression rendered almost as minutely as by the electro- 

 type process ; the mode of operation is to place a frond of fern, algae, or similar flat 

 vegetable form, on a thick piece of glass or polished marble ; by softening a piece of 

 gutta-percha of proper size, and placing it on the leaf and pressing it carefully down, 

 it will receive a sharp and accurate impression from the plant. The gutta-percha, 

 allowed to harden by cooling, is then handed to a brass-cutter, who reproduces it in 

 metal from its moulding-base. 



In 1851 Professor Leydolt of the Imperial Polytechnic Institute at Vienna, availing 

 himself of the resources of the Imperial Printing-Office, carried into execution a new 

 method he had conceived of representing agates and other quartzose minerals in a 

 manner true to nature. Professor Leydolt had occupied himself for a considerable 

 period in examining the origin and composition of these interesting objects in geology. 

 In the course of his experiments and investigations he had occasion to expose them 

 to the action of fluoric acid, when he found, in the case of an agate, that many of the 

 concentric rings were totally unchanged, while others, to a great extent decomposed 

 by tho acid, appeared as hollows between the unaltered bands. It then occurred to 

 Professor Leydolt that the surfaces of bodies thus corroded might be printed from, 

 and copies multiplied with the greatest facility. 



The simplest mode for obtaining printed copies is to take au impression direct from 

 the stone itself. The surface, after having been treated with fluoric acid, is washed 

 with dilute hydrochloric acid and dried ; then carefully blackened with printer's ink. 

 By placing a leaf of paper upon it, and by pressing it down upon every portion of the 

 etched or corroded surface with a burnisher, an impression is obtained, representing 

 the crystallised rhombohcdral quartz, black, and tho weaker parts that have beea 



