80 J. WaicrhoLisc — The A^) plication of ]?}iolo()rapli if [No. 2, 



port is said to be advantageous with small pictures, but I have not found 

 it answer very well in this country. 



All these operations, which seem so complicated, are in reality very 

 simple, and as the sensitised tissue is very sensitive to light a great many 

 prints can be produced in a single day. The number may, moreover, be 

 increased by a j^lan proposed by Capt. Abney, R. E., of exposing the print 

 for only half the usual time and then letting it lie by in the dark for some 

 hours. The decomposing action set up by the light goes on in the darkness, 

 and on development a picture is produced quite as good as if it had received 

 a full amount of exposure and been developed at once. This discovery is 

 largely utilised by those working the process in England, and enables an 

 amount of work to be done in the winter months which would otherwise 

 be impossible. 



The single transfer process has been successfully worked at the Sur- 

 veyor General's Office in Calcutta for the production of photographs of the 

 convicts transported for life to the Andamans. No great difficulties were 

 met with in working it, even in the hot weather, but it was found necessary 

 to ice the solution of bichromate of potash used for sensitising the tissue, 

 and to add a certain proportion of spirits of wine to it, in order to keep the 

 gelatine from softening too much. Messrs. Bourne and Shepherd, the well- 

 known Indian photographers, have made arrangements for working the 

 Autotype process at Simla, the climate of Bombay having been found 

 unsuitable. 



The pigment prints are perfectly permanent for all practical purposes, 

 and, though they may under certain circumstances change colour slightly or 

 lose their brilliancy, there is no such absolute fading and loss of details as 

 in silver prints. The process may be applied in all cases to replace silver 

 printing where permanenc}^ of results is an object. As I have mentioned 

 before, the process is not quite suitable for the reproduction of coloured or 

 shaded maps, owing to difficulties in obtaining prints comprising large sur- 

 faces of clean white paper together with the delicate half tones of hill- 

 shading. For maps in line the simple carbon process is more suitable, or if 

 many copies are required, photozincography would be better. 



Anilin Printing. — Before proceeding to the consideration of the pro- 

 cesses employed for producing prints in the printing press, mention may be 

 made of an ingenious process of printing which depends upon the use of 

 salts of chromium, and is largely used in Europe for the reproduction of 

 maps and plans. It is known as the 'Anilin printing process' and is the 

 invention of Mr. J. Willis, who has patented it. 



Paper is impregnated with a solution of bichromate of potash to which 

 a little phosphoric acid has been added. After exposure to light under a 

 transparent positive, such as a drawing on thin paper or vellum cloth, or even 



