PHYSICAL fllARACTEnS OP HIE SOIL. 1(57 



ingieclieuts. {Jour, filr prakt. Chem., 13d. 98, j). 476.) 

 Their results relate chietly to these substances as ordinarily 

 occurring exposed to the atmosphere, and therefore more 

 or less moist. The following Tahle includes the more im- 

 portant data obtained by subjecting tlie substances to a 

 temperature of 284° F., and measuring and analyzing the 

 gas thus expelled. 



From these figures we gather : 



1. The gaseous mixture which is contained in the pores 

 of solid substances rarely has the composition of the at- 

 mosphere. In but two instances, viz., with gypsum and 

 precipitated carbonate of lime., were only oxygen and ni- 

 trogen absorbed in proportions closely apj^roaching those 

 of the atmos])hei"e. 



2. Xitrogeu ajjpears to be nearly always absorbed in 

 greater proportion than oxygen, and is greatly condensed 

 in some cases, as by peat, hydrated oxide of iron, and car- 

 bonate of masrnesia. 



