298 SILVER 



titative by allowing NH4OH to stand therein for several hours to dis- 

 solve silver precipitated by the tissue chlorides. Samples in the cups 

 were dried under infrared and counted with an end-window Geiger tube. 

 In a study with carrier-free Ag'"« (half-life, 8.2 days; gamma, 1.63, 

 0.69; K) from cyclotron production, the tissues were ashed at 500°C, and 

 the ash spread evenly on porcelain dishes for Geiger counting (Ag-3). 

 The self-absorption curve for correction of sample counts was prepared 

 as follows: A solution (0.1 ml) containing about 3000 counts/min was 

 added to a dish which had been previously treated with a few milligrams 

 of an aerosol to promote spreading. The activity was measured in the 

 same way as the samples. Dilute HNO3 was stirred into the dish to give 

 additional mass, and the sample recounted. This was repeated, and the 

 sample was counted after every addition of mass. After the last portion 

 of dilute acid was added, the activity at zero mass was determined by 

 evaporating the solution to dryness and recounting the activity in the 



In a study with Ag^^", the tissues were digested in Kjeldahl flasks with 

 H2SO4 plus several crystals of CUSO4. After cooling and dilution, AgN03 

 was added as a carrier, and the silver precipitated in small beakers with 

 NaCl. The precipitates were collected and dried for Geiger counting 

 (Ag-4). 



Ag-1 West Harold D., Alfonso P. Johnson, and Charles W. Johnson: The Use of 

 ' Radioactive Silver for the Detection of Abscesses and Tumors. I. The Con- 

 centration of Agiii in Spontaneous and Experimentally Induced Abscesses, 

 J. Lab. Clin. Med., 34: 1376-1379 (1949). . „ -c. u , 



Ag-2 GammiU, James C, Brownell Wheeler, E. L. Carothers, and P. F. Hahn: 

 ' Distribution of Radioactive Silver Colloids in Tissues of Rodents FoUowmg 

 Injection by Various Routes, Proc. Soc. Exptl. Biol. Med., 74: 691-695 (1950) 

 Ag-3 Scott, Kenneth G., and Joseph G. Hamilton: The Metabolism of Silver in the 

 Rat with Radio-silver Used as an Indicator, Univ. Calif. Berkeley Pubis. 

 Pharmacol. JS211, 2: 241-262 (1950). 

 Ag-4 West Harold D., Raven Rivera Elliott, Alphonso P. Johnson, and Charles 

 " W. Johnson: In Vivo Localization of Radioactive Silver at Predetermined 

 Sites in Tissues, Am. J. Roentgenol. Radium Therapy, 64: 831-S34 (1950). 



