AGRICULTURAL EXPERIMENTS. 239 
I only give the results of the experiments at the two 
highest temperatures, as these come nearest to the Ceylon 
temperatures. 
‘“Cubie centimetres of water vapour condensed by 
100 c.c. of 
At Humus. Hydrated oxide ofiron. Quartz. 
20°c (68°F) 26,789 98,990 277 
-30°c (86°F) 16,497 54,753 99 
Carbonate of Lime, Kaolin. 
962 1,541 
233 i eap.” 
From these figures it is easy to see how valuable oxide 
of iron and humus must be in our Ceylon soils to enable 
them to resist drought. 
“Of ammonia gas 0°c. the following quantities were 
absorbed :— 
By humus. By hydrated oxide of iron. By Quartz. 
29,517 38, 992 938 
By carbonate of lime. By Kaolin. 
.002 
having been made at the freezing temperature the ab- 
sorptive powers of all are of course greatly higher than 
at temperatures prevailing in Ceylon. 
**To show the influence of oxide of iron on the ab- 
sorption of nitrogen by the soil, the author made the 
following determinations, in which ferruginous sand and 
clay, and the same substances freed from iron are com- 
pared in their absorptive power for nitrogen. 
100 c.c. of sand containing iron absorbed 217 c.c. nitrogen. 
do pure a 101 c.c. 
. 100 c.c. of kaolin containing iron,, 1,687 c.c. a 
do pure se 846 c.0. a 
In the absorption of the oxygen, gypsum stands higher 
than oxide of iron and next to it for the condensation 
of nitrogen. 
T trust the forgoing may be of interest to some of 
your readers. M. G 
SHINGLING. 
Not one half the persons who lay shingles when 
making a roof on a building have any correct ideas — 
in regard to making a roof that will be absolutely rain- 
tight during a driving storm of rain. We have fre- 
quently seen men shingling, who, when they would 
meet with a worthless shingle, say once in laying two 
or three courses, would lay this poor shingle among the 
good ones, saying, ‘‘Itis only one poor shingle, one 
shingle cannot make a poor roof.” But one poor 
