GRAIN CONSERVATION 133 



of the experiment it was found that in one flask 58*6 

 milligrams of C0 2 had been formed, and in the other 

 56 milligrams ; in the former the percentage of 

 C0 2 in the air in the flask was found to be 18*13, 

 and in the latter 17'82. 



The rate at which carbon dioxide is given off 

 varies according to the amount of moisture present 

 and according to the temperature, but in actual 

 practice this could perhaps be regulated as desired. 

 We have already had occasion to notice the large 

 amount given off by wheat containing 20*7 per 

 cent of water at about 31 C. (88 F.). 



If insects are present in the grain, the percentage 

 of carbon dioxide rises more rapidly because the 

 insects themselves produce very considerable quan- 

 tities of this gas as a result of their own meta- 

 bolism. Thus it was found that at room temperature 

 (63-66 F.) 100 rice weevils (Calandra oryzae) gave 

 off 23'5 milligrams of carbon dioxide in 48 hours, 

 while 100 grain weevils (Calandra granaria) gave 

 off 19'7 milligrams. 



Analyses have also been made of the gases present 

 in the flasks in which weevils had been sealed up 

 until they were killed. These experiments were 

 made at 31 C. (88 F.), a temperature very favour- 

 able to the weevils under ordinary conditions. One 

 hundred rice weevils were sealed up for 72 hours, 

 with enough killed grain for them to feed upon, the 

 killed grain giving off only a negligible quantity of 



