X-Rays, Apparatus and Methods Page 19

current through the primary when such sticking occurs. Upon release, therefore, a secondary discharge much above normal is produced, and this the parallel spark gap is unable to carry off. The tube, therefore, receives much more energy than it should, and may break down even though the parallel spark gap be as advised by the manufacturers.

(b) The Plate and Its Development. — We have used at one time and another a number of different makes of plates with very fair success. For some time past we have confined ourselves to the Carbutt X-ray plates, and though we are not prepared to say that they are the best plates to use, the results are so uniformly good as to make it seem advisable to us to try other plates not radically different in principle.

For developer, we use the Carbutt "J. C. tabloids"—3 J and 3 C, to 5 ounces of water — add about 2 drachms of restrainer (the usual 10 per cent. solution). Heating this developer to about 65° or 70° F. just before using, we also find to have beneficial results.

From 15 to 20 minutes will be required for development. The image will come up very slowly and not very sharply. Not much detail will be visible by holding up to the light. Continue development until the general main outlines have appeared and faded away to a general blackness upon the glass side. Then rinse and hypo.

The fixing generally requires from a half hour to two or three hours. This long time is probably partly due to the unusual thickness of the Carbutt X-ray films, but probably even more to some chemical condition set up by the unusually large quantities of restrainer used. Mr. Carbutt advises 3 J and 3 C tabloids to 6 ounces of water to 20-30 drops restrainer. Our experience is that a plate so developed always requires intensification; a tedious nuisance, which can never give as good results as a normally exposed and developed plate.

Fluoroscopy. — As a really efficient aid to investigation or to surgical practice, the fluoroscope has thus far proved rather disappointing. In case of very definite fractures of arm or of leg below the knee, as also in certain cases of gunshot wound in these same parts, the fluoroscope will afford definite knowledge.