QOi IOWA ACADEMY OF SCIENCE 



Table XVII. Formaldehyde Vapor— Effect of Temperature. 



Iii the above table (d) was raised to 60 degrees C. at the 

 start and a second time after the treatment had been under 

 way for five minutes. Treatment (e) was maintained at 75 de- 

 grees for five minutes. All others were simply started at the 

 temperature designated. Some condensation took place on the 

 grain under treatment (a) which may have injured the germina- 

 tion. 



When the formaldehyde solution was heated the gas was much 

 more effective. However, at the higher temperature 75 de- 

 grees C. for one-half hour a lowering of the germination was 

 noticeable, due probably to condensing of the vapor on the grain. 

 (See Table XVII.) 



Further work with formalin vapor and formalin solution 

 showed both to be ineffective in killing the spores within in- 

 fected wheat grains. Other factors which may influence the 

 results are mentioned, e. g., it was found that a 30 per cent 

 solution of formaldehyde after air had passed through for two 

 hours analyzed 38 per cent of formaldehyde. New chemicals 

 should be used for each treatment to eliminate error. 



