Page:The American Bookmaker - Volume 12.djvu/82

50 pear as cannot be laid to the fault of the negative, but are evidently due to poor process work or to bad presswork.

In January last a new periodical was issued at Guadalajara, Mexico, entitle Jalisco Illustrado, of which has received a copy. It has a very artistically engraved head, and is clearly printed on a very good quality of paper. This initial number is not very greatly adorned as to its pictorial features, the illustrations consisting of a full page process portrait of General Galvan, a street scene in Guadalajara and some cuts of a humorous character.

In "Electricity in Daily Life" Scribner's Sons have issued a handsome 8vo upon a subject which afforded a fine opportunity for the art of the illustrator. Certainly there has been no chance for just complaint on the score of neglect in that direction, for the different branches of the subject are abundantly illustrated with engravings of a superior character which serve to make more plain the matter in the text relating to electric motors, electric lighting, telegraphs, submarine cables, electricity in the household and in warfare, on land and sea, and as applied to the human body. Such illustrations add almost incalculable value to a book of this character, and the fact that they are numerous and and of uncommon excellence is very gratifying and in the work above named very noticeable.



N order to convert stereos of photo engravings into letterpress plates, the perfect execution of the line engraving is of the utmost importance. This is no easy matter. Nevertheless, the excellence of the result depends on perfection in this respect. The clearer the line work—black in the white lines and in the hollows—the better will be the proof which will serve for the impression on metal of the sensitive covering of bitumen or bichromated albumen. A tracing is used to reproduce in the dark chamber a positive on glass placed behind this tracing in such a manner that the contact of the two surfaces, that of the tracing and that of the positive, is as complete as possible. The linear negative which results is formed by white and black spaces, without the least half tint. With this negative the printing is done on bitumen, and then bitten in. If this operation is performed under favorable conditions, no retouching is necessary. Léon Vidal recommends this process to persons desirous of transforming ordinary negatives into stereos. In the case of these negatives collodion is indispensable, and the transitions from black to white should be very clearly defined.

NEW method of lichtdruck, invented by O. Schwartz, is described as follows: As bottom layer serve a mixture of the following ingredients: Take 30 parts of the white of an egg which has been beaten to foam, 30 parts of water, one-half part potassium and one-half part of bichromate of ammonia. With this cover the plate glass, and dry the layer by placing it upright; then put the glass plate upon a black piece of cloth and let the light reach the layer through the glass, which will make it insoluble, and whereby it will become firmly adhesive. The layer which is to serve for printing consists of the following mixture: Two parts of isinglass, 25 parts of water, 8 parts gelatine which has previously been soaked in water, 1 part bichromate of ammonia, and one-twentieth part of chlorate of calcium.

These ingredients are mixed after having been heated somewhat, and then the mixture is poured upon the glass plate and dried at a temperature of 50° centigrade. It is thereafter exposed to light under the negative and washed with pure water. As a means of hardening, use a 1 per cent. solution of alum; for etching, 10 parts of water with 1 part nitric acid, and saturate this solution with carbonate of calcium and add thereto an equal part of glycerine and a trifle of permanganate of potassium. Leave the plate uncovered for half an hour, and then proceed with the printing.