Show Radium N Now Nv v Used to Discover Flaws F Buried Ten Inches ip jn if Steel Plat PHILADELPHIA Nov 26 SS- SS SS Using a diminutive capsule of radium ra ta- ta salt instead of an elaborate ray X-ray c camera era engineers now take pictures picture through steel as a much as asten s ten Cinches thick in search of threat teatA threatening ening cracks and flaws With recently developed technique technique tech tech- Wih hU tec castings for big guns of the U. U S S. S1 navy nav are made t to reveal their weaknesses before they can can be fired tired d disastrously and electric welds weld are tested tese without actually breaking the joints These Tee are ar some of the applications of testing with gamma gama rays of ot radium radium ra raA ra- ra described before the ray Franklin Institute by Dr r. r Gilbert E E. Doan Doa of Lehigh university Bethlehem Pa Dr Doan was active In research work which developed t these e methods method rays X-rays have been used for some industrial testing he pointed point ed out But the ray X-ray method is s satIsfactory satisfactory sat sat- t. t only for relatively thin metal and requires require extensive apparatus appa apparatus ratus rat voltage high hIgh electric current and d trained operators If U the te steel 1 object were more than more than three tre inches thick it i took tok so s 's long for the rays X-rays to t blacken the film fm that the was wa hopelessly ly slow and cOty costly Dr Doan said Now Nov Nov- since nince scientists have learned leared how ito to use ue gamma rays they can cante te test t thicker casting more rapidly and with much much less trouble he he- he explained All Al that Is is' required Is i a a capsule of radium salt al the size of ot ota a a pea and ordinary ordina photographic paper paper The radium is put a short distance from the metal on one side and th lix t photographic film film- wrapped in buc fm sl i paper Is I laid against the other ote of th the test tet specimenS specimen n. n The time of ofu a X depends on the a a few minutes minute being s in most mot cases caes The developed film fUm reveals reveal the te li in i tenor Ledor ci of the th metal just as as si an n K-n Knof of ones one's teeth tel gives gives' the location of i I abscess More gamma rays rays' p Pl abse through trough the fractured or h hole Ww le ed part of the metal to to act act On ct on on ft tl film fi e than come come tough through where whee u tb th metal is sound soud In Jn the course cours of ot he Dr Doan found that the e e ewas was im unusually u ly long because e the te en em nation from radi radium m was Wa J through the emulsion emulio of ot t the thi without changing it It chemically chemically- remedy was wasas waa as simple as it was wa oo od Sheets of lead foil oi or or of were ere wrapped around aroud the film fil Then The In P- P through this covering the rays lib li though te ray crated electrons from it ad and ia th te crat secondary radiations sped sl U UP W th t blackening of of the film m Although already used by byl byse uv large large corporations and by tj the cu navy navy the gamma ray method metho ci t w Hd lag Ing lg has ha not yet found application Dr Doan Dean said uld |