VII. 1'HOTOGUAPHY. 205 



At the application of the negative process, Rupell's drying system, with 

 tannin, has been employed. The positive prints are either black silver copies 

 or blue iron pictures, to which preference is given in case the photograph is 

 to be traced over with Indian ink, and the photographical ground to be 

 removed afterwards by etching for the purpose of producing a clean drawing. 



1 . Reproductions of Central Asiatic surveys and maps. 



2. Copies of surveying plate sheets in European Russia. 



952b. Photolithography. 



The Topographical Department of the Imperial Russian 

 General Staff at St. Petersburg. 



Transfer on stone of a printable picture, well covered with ink, which has 

 been produced on a gelatine ground rendered primarily sensible by double 

 chromate of potash. 



Reproduction of a Hebrew manuscript of the 10th century, belonging to the 

 Imperial Russian Public Library. 



952c. Hello-Engraving. Sediment of galvanic copper on a 

 photographical gelatine relief. 



The Topographical Department of the Imperial Russian 

 General Staff at St. Petersburg. 



Copies of a heliographical edition of the survey of Bessarabia, on the scales 

 of 1 : 100,000, and 1 : 126,000, and the survey of Finnland, scale, 1 : 42,000 ; 

 map of Khiva, scale, 1 : 580,000, transferred on stone, and prepared as colour 

 print. 



952 d. Examples of Helio graphic and other Processes. 



Imperial Establishment for the preparation of official 

 papers, St. Petersburg. 



1 . Portfolio of heliographic copper-plate and mezzo-tint engravings by the 

 process of G. Scamoni (manager of the Heliographic Department of the 

 Establishment), containing : 



27 reproductions of historical portraits ; 



10 reproductions of fine engravings ; 



12 reproductions of etchings ; 



8 reproductions of drawings executed with pen and ink, water-colour, 



and crayon ; 



17 reproductions of pen and ink drawings ; 

 6 reproductions of wood engravings. 



2. One heliographic plate in electrotyped copper. 



3. One heliographic plate in electrotyped iron. 



4. One typographic printing form in electrotyped iron, from type. 



5. One typographic printing form in electrotyped iron, net-work from 

 type. 



6. One typographic printing form in electrotyped iron, net-work from 

 relief. 



7. One typographic printing form in electrotyped iron, guilloched net- 

 work. 



8. One typographic printing form in electrotyped iron, id -annealed. 



9. A glass plate, with the surface irregularly broken up into floral and 

 other forms through a coating of gelatine ( millimeter thick), springing up 

 from it when dried at a temperature of about 70 C., thereby producing a 

 form, from which an inimitable printing-plate can be made. 



10. Handbook of heliography, by G. Scamoni. 



