228 PHOTOMICROGRAPHY 



a good photomicrograph. It is generally essential that 

 the detail present in the negative be transferred to the 

 paper without loss, but sometimes it is necessary to 

 obtain as great contrast as possible in the print, even 

 though this may involve a slight loss in the delicate half- 

 tones and detail. Convenience may decide whether it is 

 better to employ a paper that is printed out in daylight, 

 or whether a development paper that only requires a 

 short exposure to artificial light followed by development 

 is to be used. Most papers can be obtained in a variety 

 of grades with glossy, semi-glossy, matt, or rough surfaces. 

 The glossy give the most detail, and the rough are prac- 

 tically useless for photomicrographs. 



Printing-Out Papers. There is no paper like glossy 

 " P.O. P." for the reproduction of fine detail, and it is 

 generally the best paper to select for use with good 

 negatives, when daylight printing can be resorted to. 

 The manipulation is simple, and details are given in the 

 packets. 



Self -toning papers are the simplest of all to use, and 

 require fixation only after printing, but as a rule some 

 loss of detail is apparent in comparison with a toned 

 P.O.P. print. 



Development Papers are broadly divided into two 

 classes " Gaslight " and " Bromide." Their manipula- 

 tion is practically identical, except for the length of 

 exposure required. Bromide papers must be worked in 

 yellow or red light ; gaslight papers will not fog even if 

 the room is lighted by gas, provided they are not exposed 

 directly to it, and reasonable care is taken to shield them 

 during development, etc. The paper is placed with the 

 negative in a printing-frame, and exposed to the il- 

 luminant for the required time. Different brands vary 

 in speed, but bromides may be expected to require only 

 a few seconds at two feet from a 16 c.p. electric light, 

 while gaslight papers require J to several minutes at one 



