. Radiography, X-ray therapeutics and radium therapy . as found that if a limb of eventhickness was radiographed, being divided into areas which allowed of twelveexposures of different duration, commencing with 2 seconds and ranging upto 20 to 30 seconds, useful negatives were obtained from each exposure. PRACTICAL POINTS IN EXPOSURE 103 The development was necessarily uniform, as all the exposures were on theone plate. Second Experiment.—On this occasion the same duration of exposurewas given to each part, and it was found that useful negatives were obtainedby varying the time of development.
. Radiography, X-ray therapeutics and radium therapy . as found that if a limb of eventhickness was radiographed, being divided into areas which allowed of twelveexposures of different duration, commencing with 2 seconds and ranging upto 20 to 30 seconds, useful negatives were obtained from each exposure. PRACTICAL POINTS IN EXPOSURE 103 The development was necessarily uniform, as all the exposures were on theone plate. Second Experiment.—On this occasion the same duration of exposurewas given to each part, and it was found that useful negatives were obtainedby varying the time of development. Third Experiment.—This experiment was carried out with a view toascertaining the influence of temperature on the action of the developingagent. A wide range of variations was found which are very the same exposure for two plates and developing them side by side,one solution being about 20 per cent, colder than the other, it was found thatat a temperature of 60° development was rapid, detail good, and density Exposure2 Fig. 88.—To illustrate the latitude of exposure. Exposure with a hard tube. correct. If the temperature was below 45° the resulting picture showeddetail, but little density, indicating that the hydrokinone had not been ableto use its influence. Fourth Experiment.—On this occasion variations in exposure were made,the times of exposure being as 1 to 5. The plate exposed for the shortertime was developed at 60° and the other at a low temperature. It wasfound that the first plate gave the better result. These experiments indicate that by giving minimum exposures the wearand tear on apparatus and tubes is lessened, and the fogging of plates bysecondary radiations avoided, while by proper manipulation of the developingsolution better pictures are obtained. A further advantage of using the 104 RADIOGRAPHY developer at a proper temperature is that we lessen the risk of fogging theplate by prolonged exposure to even a safe ruby light
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