142 



THE PRODUCTION OP POSITIVES, ETC. 



All the trouble of the foregoing manipulations 

 may be avoided, by purchasing the paper ready 

 coated. An excellent quality is supplied by Morgan 

 and Co. In fact we recommend all to whom time is 

 of value, to purchase everything from those whose 

 business it is to manufacture articles of this descrip- 

 tion, as in the majority of cases home production is 

 false economy. 



The extreme sensitiveness of this paper renders 

 printing by contact, especially by daylight, a rather 

 difficult matter, unless the light is subdued by plac- 

 ing tissue paper or muffed glass a couple of inches 

 in front of the printing frame. The exposure can 

 then be prolonged, a great advantage when accurate 

 results are required. It should be remembered that 

 the intensity of the illumination and duration of the 

 exposure have more influence on the condition of the 

 resulting positive than the character of the negative 

 itself. For instance, a very thin negative may be so 

 weakly illuminated that a harsh positive is the re- 

 sult; while a very dense negative, if exposed to 

 bright sun-light, will produce a positive completely 

 wanting in proper contrast. Advantage should be 

 taken of this and the illumination arranged to suit 

 the character of the negative. 



It is evident from this that no rule can be given 

 for exposure when daylight is employed, and even 

 with lamp light, owing to the variations in density 

 of different negatives, an approximation only is pos- 

 sible. At the same time an over-exposed negative 

 always gives the best results, as a weak light and 



