308 SULFUR 



a temperature below red heat until the charge is oxidized. The mixture 

 can then be taken up in HCl solution, made to volume, and filtered. 

 BaS04 is precipitated by standard methods; collected, washed, and 

 weighed for estimation of sulfur; and plated out for radioassay. In the 

 egg^studies the S^^ in the albumen and yolk was characterized as dialyz- 

 abte sulfate S, dialyzable organic S, nondialyzable sulfate S, and non- 

 dialyzable organic S. Also cystine and methionine were isolated from 

 albumen hydrolysates by ion-exchange chromatography on Dowex 50 to 

 determine the extent of incorporation of the administered sulfate S^^ 



Carius Procedure. Reference (S-8) may be consulted for a detailed 

 description of the Carius benzidine sulfate procedure for estimation of 

 8=*^ in various biological materials. In general, the sample is placed m 

 the pyrex glass bomb together with NaBr and red fuming HNO3, and the 

 bomb sealed and heated at 300°C in a Carius furnace for not less than 

 4 hr. The contents of the bomb are washed into an evaporation tube and 

 taken to dryness. The residue is dissolved, 95 per cent ethanol added, 

 and then the benzidine hydrochloride reagent. The precipitate of ben- 

 zidine sulfate is centrifuged and resuspended in 95 per cent alcohol and 

 can be collected for counting by one of the methods outhned in Chap. 5. 

 Autoradiographic Procedure. Two milligrams of sodium sulfate con- 

 taining 8.24 X 10^ counts/min was injected intraperitoneally into a 

 suckhng rat (S-9). The bones were trimmed of soft tissue and fixed for 

 24 hr in 3.7 per cent Formahn. The bones were embedded in paraffin 

 and cut at 7 m, and sections transferred to sHdes coated with egg albumin. 

 The paraffin was removed with xylol, and the mounted sections covered 

 with Kodak Process Ortho film. The top surface of the section was kept 

 about 20 M from the emulsion surface by a narrow strip of glassine paper 

 placed at each end of the shde. A clean shde was used as backing for the 

 film and the assembly was held together by rubber bands and wrapped 

 in black paper for the 3- to 7-week exposure. The film was developed 

 and the sections subsequently stained with hematoxyhn eosm or with 



toluidine blue. 



Bean leaves infected with rust or powdery mildew or sunflower leaves 

 infected with rust were detached from greenhouse plants and exposed to 

 vapors from 50 ml of 0.01 per cent NaaS containing 5 to 8 mc S^^ at pH 8 

 in sealed pint jars for 8 hr at about 22°C (S-10) . The greater absorption 

 of S^^ by the infected leaves was demonstrated by autoradiograms made 

 with X-ray film using an exposure of 48 hr. Locahzed areas of the leaves 

 2 to 13 mm^, were measured by use of a Geiger counter and a perforated 

 lead shield. References (S-11, S-12) may be consulted for techmques m 

 the use of 8^° with crop plants. ^ u ^ a 



A study has been reported on the preservation of silage with S^^-labeled 

 SOo and the fate of the S^^ when the silage was subsequently fed to the 



