TRANSACTIONS OF SECTION B. 339 
In a graph plotted with daily concentrations of total (nitric plus nitrous) 
nitrogen as abscisse, and with rainfall as ordinates, the points are found to 
arrange themselves into a series of rectangular hyperbole. Further, each group 
of points lying along a particular curve is found to correspond with falls of rain 
occurring during one particular type of weather. From this it follows that for 
a particular type of weather (1) the concentration of oxidised nitrogen varies 
inversely as the rainfall; (2) the product of the concentration and the rainfall is 
constant; (3) the total weight per unit area of oxidised nitrogen precipitated 
with rain falling during twenty-four hours is constant. In brief, the amount 
of oxidised nitrogen per acre carried down by rain falling on any day is a 
function of the type of weather, and, within certain limits, is independent of 
the amount of rainfall. These facts may be explained by assuming that for 
each type of weather there exists in the air a definite concentration of nitrogen 
peroxide, and that this soluble gas is completely washed out of the air by the 
first portions of a shower: any further rain falling through the now purified 
air not increasing the amount of oxidised nitrogen in the rain-water, but, by 
dilution, decreasing the concentration. 
Nine well-defined recurring types of weather have been investigated. These 
may be classified into three groups, as follows: (1) Antarctic types; (2) Tropical 
types ;.(3) Divided control (Antarctic and Tropical) types. The accompanying 
table shows the number of examples of each type investigated, together with 
the oxidised nitrogen constant in pounds per thousand acres, for each type. 
es. | Oxidised Nitrogen 
| bala ae Constant. Pounds 
| Memes ale per 1,000 acres 
| Antarctic Types— f | 
E BEeeTR Nas <a Bd 5 
A-shaped Antarctic | iS peost : ; x 38 oe 
depressions | (Ey onto 10 41 
Tropical Types— 
_ Tropical (or f (g) spring and autumn type . 6 
monsoonal) } (kh) summertype . .. 3 24:0 
depressions (i) ‘heat-wave’ type . . 2 
| Divided Control Types— | 
(d) Antarctic depressions with slight Tropical | 
| IRUENGEN 8 ugh Malis: vliehee oi Ack 6 6-1 
| (e) Antarctic depressions with strong Tropical | 
| TAM CAGEe ATS eo (taka. Yantai outl ana 8:5 
(f) Tropical depressions with slight Antarctic 
influence. rae eee: 5 12:0 | 
4. A Comparison of the Phenomena of the Occlusion of Hydrogen by 
Palladium and by Charcoal. By Dr. A. Hour. 
When all the known facts concerning the occlusion of hydrogen by palladium 
and by charcoal are examined and compared, it appears that, in the case of 
charcoal, absorption and surface condensation, without chemical action, occurs, 
but with palladium the evidence is in favour of the formation of a compound 
in addition to surface condensation. In both cases there is evidence that allo- 
tropes of the occluding solids exist, one allotrope occluding gas with far greater 
avidity than the other. 
7% 2 
