PHYSICAL CHARACTERS OF THE SOIL. 167 
ingredients. (Jour. fir prakt. Chem., Bd. 93, 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 19 Vols. 109 Vols. of Gas contained : 
Ee 
yielded gas yielded — ———_——— 
Substance an vols.  Nitro- Oxy- Carbon- Car- 
> C. C. gas. gen. gen. tcacid. bonic 
: oxide. 
Charcoal, air-dry, 164 — 100 0 0 0 
of moistened and dried again, 140 59 85 2 9 3 
Peat, 162 — dt 5 51 0 
Garden soil, moist, 14 20 64 3 24 9 
me “air-dry, 38 54 65 2 33 0 
Hydrated oxide of iron, air-dry, 375 309 25 4 79 0 
Oxide of iron, ignited, 52 83 13 4 0 
Hydrated alumina, air-dry, 69 82 41 0 59 —— 
Alumina, dried at 212°, au! 14 §3 17 0 — 
Clay, 3: — 65 21 14 — 
** Jong exposed to air, 26 39 8 5 23 — 
‘© moistened, 29 Bi) 60 6 34 — 
River silt, air-dry, 40 48 68 0 18 14 
= ‘** moistened, 24 29 67 0 31 2 
a ‘© again dried, 26 30 67 9 16 i 
Carbonate of lime (whiting,) 1864, 43 52 100 0 0 _— 
i Shs. a 1865, 39 48 74 16 10 — 
$ “eS precipitated, 1864, 65 a 81 19 0 a 
, = otis oe 1865, 51 52 U7 15 8 — 
Carbonate of magnesia, (29 125 64 7 29 — 
Gypsum, pulverized, 17 _ 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. 
