36 



PHOTO-MICROGEAPHY 



(ii) MAKING LANTERN SLIDES 



We next proceed to explain how to make lantern slides from the negatives 

 obtained photo-micrographically. Plates ready made are sold by most makers, and 

 each claims superiority of manufacture. They are primarily of three kinds : ordinary 

 gelatin, printing-out gelatin, and collodion. Of these the gelatin are by far the easier 

 to work, as they possess much latitude in exposure, whereas the collodion type, 

 whether ready made or manufactured by the photographer himself, must have exactly 

 the right time given them, or they are of no use. 



With respect to plates made with gelatin emulsion, they may again be divided 

 into rapid and slow. It is not easy to define accurately the advantages or dis- 

 advantages of either, but speaking generally the rapid type give black images, 

 whereas the slow are more amenable to treatment and produce pictures much more 

 warm and soft. Almost any colour may be obtained with them if the directions 

 enclosed in each box are carefully carried out. Then, again, if one is unable to obtain 

 detail known to exist in a negative with a quick plate, the prudent experimenter will 

 surely try a slow one, and if unsuccessful again, try his luck with one of the prmtmg- 

 out type. 



For the subject in hand— the production of lantern slides from photo-micro- 

 graphically obtained negatives, especially in the case of medium and high-power 

 work — seeing they are more dense, and require such careful exhibition of detail and 

 as there are many who consider that rapid emulsions give more gradation than slow 

 ones— although this is not a universally accepted statement— so we have mostly found 

 that the rapid series of lantern plates suit our purpose the better. As to the finest 

 maker, we cannot be expected to advise, but what we use ourselves and can find no 

 fault with are those prepared by the Paget Prize Company, the "Rapid" series. 



Let one be placed on the negative as it lies in the printing frame, having first 

 carefully examined its film to see that no little pieces " stick up " from the edges— an 

 attempt at " frilling " of the plate. If these bits are present they will be found to be 

 very hard, and will resist the accurate contact of the lantern plate against the film of 

 the negative so effectively as to prevent the best result being obtained. Let them be 

 scraped off with a sharp knife. Seeing that the lantern plate lies in sharp contact 

 then, the frame is held in front of the gas flame at a distance of a foot, taking care to 

 move it about as mentioned when explaining a little later on the exposure of Nikko 

 paper. A good negative of the proboscis of a blow-fly will require about five 

 seconds; ten will not hurt it, as there is so much latitude with these lantern 



