Foliotypes.
Horace M. Engle, Esq., of Marietta, Pa., has devised a method of taking leaf-prints of marked beauty, which he terms “foliotypes,” some specimens of which he sent to Dr. Gray, the eminent botanist, who pronounced the process a new way, and advised him to send an account of it to the Botanical Gazette, which he generously did. We have employed the method according to the explanation there given (which we reprint in full) with the most delightful results, having secured prints of some beautiful leaves which are faithful to nature in color and outline, with all their delicate tracery: “The method is of actual usefulness to the botanist, as well as a refining recreation for others who love Nature ‘on general principles.’ For illustrating monographs and similar papers, where the number is too limited to warrant an expensive lithograph; for identifying a rare specimen, or as an adjunct to an herbarium, combining portability, unalterability, and beauty withal the method seems particularly fitted. But aside from this others may find a delightful and instructive recreation in taking prints of the entire flora of the old farm, the trees of a certain grove, the native annuals of a county, the ferns of a State, or any other special field that seems most inviting. Such copies may be taken in a blank book suited to the purpose, or, better, take them on single sheets of uniform size, as in this way imperfect copies may be thrown out, and when the work is completed they may be named, classified, and bound, making a volume of real value and worthy of just pride.
“The process consists in using the leaf for producing an impression as a printer uses type, the ink being green, and the pressure applied either by hand or with a press. There will be needed for the work (1) a small ink roller such as printers use for inking type by hand in taking proofs; (2) a stout window glass (10×12 is a good size) fastened securely (not glued, as it may warp and break,) to an evenly planed board about twice its surface, say 10×24. A small quantity of the ink is put on the glass and spread with a knife, after which it is distributed evenly by going over in all directions with the ink roller. When this has been carefully done the leaf to be copied is laid on a piece of waste paper and inked by applying the roller once or more with moderate pressure. This leaves a film of ink on the veins and network of the leaf, which should then be placed on a piece of blank paper and considerable pressure applied for a few moments. When the leaf is removed from the paper the work is done.
“To get the best results several points must be carefully noted. Get a quarter or half a pound of dark green ink, which is put up in collapsible tubes costing from fifty cents to $2 per pound, according to quality. As sold it is invariably too thick for this purpose, and should be thinned by adding several drops of balsam of copaiba to as much ink as may be taken on a salt spoon. Much depends on the proper consistency of the ink. In inking the leaf is liable to curl on the roller, but it should part readily from it. In case it sticks tightly the ink is too thick. Take care that the ink is evenly distributed on the glass and roller, as it is essential that each part of the leaf receives an equal coating of ink. If the leaf is large ink it part by part, keeping the roller well supplied. A roller three inches long, costing forty cents, will answer for all small leaves and branches of plants. Clean the roller and glass with benzine after using. If the leaf is finely veined the lower surface makes the better print, but if the veins are coarse and large the upper surface may be used. If the specimen is fleshy or brittle allow it to wilt until it becomes more pliable, or if necessary it may be pressed and dried first. In most cases the best copy is obtained after taking one or two impressions, as the leaf takes the ink better after several applications. A good quality of unsized paper that is made slightly damp by placing between sheets of moist newspaper is best for general work, but in other cases well sized paper will take a copy that will allow a foliotype (may I coin the word?) to bear inspection side by side with a good lithograph. I find a copying press very valuable in making the impression, especially if the leaf is at all coriaceous. If it be soft it should be covered with a few thicknesses of newspaper. If it is irregular in thickness, paper may be laid over the thin parts, so that equal pressure is received. This is necessary with all leaves that have thick stems. If the branch is very irregular or delicate, or in the absence of a press of any kind, the specimen may be covered with several layers of paper, and held in place by one hand while the pressure is applied by the thumb or palm of the other hand as required.
“These particulars are as complete as practicable. Experiments will lead to many improvements in details. Employ tact and neatness, and you will be surprised at the result.”