Manchester Memoirs, Vol. Ix. (1916), No. 9. 1 1 



from the film after its work had been done, and in its 

 being perfectly odorless. 



In order to obtain sufficient saturation of the colours 

 in the print it was necessary to incorporate much more 

 dye into the emulsion in the case of printing from Auto- 

 chrome plates than was necessary for printing from 

 window transparencies and the like, because there was 

 considerable loss of colour in breaking through the grey 

 tone of the Autochrome screen to produce good whites. 

 This led again to a slowing down of the emulsion, and it 

 was hardly feasible to obtain a quicker printing of an 

 Autochrome of medium density than in about two hours 

 in sunlight. The Autochromes would not stand such a 

 long exposure to the sun, they became over-heated and 

 the colours disappeared, a positive in black and white 

 ultimately resulting. This effect was not due to any 

 bleaching-out of the colours, but to a melting of the 

 varnish containing the coloured starch granules, thereby 

 mixing up the colours in the film and producing an even 

 grey colour. This difficulty was obviated by withdrawing 

 the printing frame from the sun at intervals, and allowing 

 the Autochrome to cool, preferably by applying a wet 

 sponge to the glass or using some such other device. By- 

 taking adequate precautions it has been found possible to 

 print over a hundred copies from one Autochrome plate. 



I am sorry to state that the fixing of the dyes has 

 only succeeded very imperfectly. The prints may be 

 kept any length of time in albums, but they are not per- 

 manent enough to hang up in rooms for any length of 

 time without suffering. 



The sensitizers are washed out of the film, and an 

 attempt has been made to mordant the dyes, but the 

 results leave much to be desired. 



In printing from Autochromes it is necessary, in order 



