File:Discovery (20961705415).jpg

Title: Discovery
Identifier: discovery0102londuoft (find matches)
Year: [1] (s)
Authors:
Subjects: Science
Publisher: London (etc. ) Professional and Industrial Pub. Co. (etc. )
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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DISCOVERY 145 The drying of their pictures, however, presented difficulties, owing to ignorance of the difference between pure oil and siccative linseed oil ; and to remedy this the galipot method was then adoptedâthat is to say, colours were first of all ground with turpentine and then, when in the form of powder, diluted with a varnish composed of the said galipot (white resin, a sort of turpentine) and spirits of turpentine. This technique changed but little down the Ages, bringing Professor Laurie to the conclusion that as regards the instruments of their art there was practically no change from the days of Leonardo da Vinci to those of Renoir and the one to six diameters ; whereupon it became evident that, in the fight against the picture-forger, photo- graphy and its various applications was to play one of the most important of roles. To H. Parenty, of Lille, is due the credit for having discovered that by simple photography it was possible to penetrate the undeniable transparency of the layers of paint on pictures, and thus reconstitute, as it were, certain details in the works of Titian, Rembrandt, Rubens, and other Great Masters that are invisible to the naked eye. This at once led other technologists to ask themselves the question, \\'liy not employ X rays ?
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KIG. 4. â VIERGE DE STEI,I,.\- Impressionists. However, the pigments used in paint- ing did vary considerably from period to period, and by applying his method to a large number of works of absolutely certain date, the investigator with the microscope was able to draw up a chronological list of pigments of the greatest utility. Microscopic study of the pigments of a given painting enabled one, then, in many cases, to determine its date appro.xiniately and to declare whether any portions had been retouched by restorers. Advancing this excellent method one more step further, Professor Laurie took micro-photographs of minute portions of ancient canvases, enlarged from R.\DIOGR.\PH OK THE " VIERGE DE .STEI.L.\ " SHOWING D.\>L\GEU PORTION WHICH HAS BEEN RESTORED. In the centre a bar of wood prevented complete passatje of the X rays. No sooner said than done. And thus, in 1914, the first researches concerning the radiography of pictures were made in Germany by Faber, as related in the Zeitschrifl fur Museumkunde. Dr. Heilbron, of Amsterdam, continued them with most curious results. Finally, between the middle of 1920 and the present date, we find a Parisian specialist. Dr. Andre Cheron, perfecting the method to such a degree that we are tempted to say the days of the picture forger are numbered. Dr. Heilbron's results must first of all be described. As the subject for his investigations he took a " Crucifixion," by Engelbrechtsz, a picture which was

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