PHYSICAL CHARACTERS OF THE SOIL, 167 
ingredients. (Jour. fur prakt. Chem., Bd. 98, p. 476.) 
Their results relate chiefly to these substances as ordinarily 
occurring exposed to the atmosphere, and therefore more 
or less moist. The following Table includes the more im- 
portant data obtained by subjecting the substances to a 
temperature of 284° F., and measuring and analyzing the 
gas thus expelled. 
100 Grams 10 Yols, 100 Vols. of Gas contained : 
ae “vols. Nitro- Ozxy- Carbon- Car-- 
Substance » in 
Cc. gas. gen. gen. ic acid. bonic 
i oxide. 
Charcoal, air-dry, 164 _ 100 0 0 0 
“ moistened and dried again, 140 59 86 2 9 3 
Peat, 162 _- 44 5 51 0 
Garden soil, moist, 14 20 64 3 24 9 
“air-dry, 33 B4 65 2 33 0 
Hydrated oxide of iron, air-dry, 38% 309 26 4 70 0 
Oxide of iron, ignited, 39 52 83 13 4 0 
Hydrated alumina, air-dry, 69 82 41 0 59 —_ 
Alumina, dried at 212°, 11 14 83 17 0 _ 
Clay, 383 = 6 1 uw — 
‘© long exposed to air, 26 39 vA) 5 25 _ 
** moistened, 29 35 60 6 3 _ 
River silt, air-dry, 40 48 68 0 18 14 
u “moistened, 2A 29 67 0 81 2 
again dried, 26 30 67 9 16 7 
Carbonate of lime (whiting,) 1864, 43 52 100 0 0 _ 
ae eo ee 1865, 39 48 74 16 10 - 
ba «ss precipitated, 1864, 65 - 81 19 0 _ 
* fe oe ee 1865,- 51 52 vi 15 8 - 
Carbonate of magnesia, 729 125 64 q 29 _ 
Gypsum, pulverized, 1% - 81 19 0 _ 
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 approaching those 
of the atmosphere. 
2. Nitrogen appears 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 magnesia. 
