350 Ward. — Recent Publications bearing on the 
Sciences Naturelles 1 on the subject of the relations of the at- 
mospheric nitrogen to that of plants. After pointing out that 
a forest, regularly exploited, loses annually when the trees 
are cut certain quantities of nitrogen, and that large pastures 
&c. do the same, and this goes on year after year without 
any apparent restitution further than what is afforded by the 
manure of animals, decay of organisms, &c., he then proceeds 
to show that the opinion gains ground that the soil seems to 
lose more combined nitrogen than it receives, and the only 
explanation of the anomaly is that the atmosphere’s free 
nitrogen intervenes. 
The author then considers the question of the losses and 
gains in nitrogen of cultivated soils. 
Regarding, first, the losses : they are as follows : — 
(1) Losses of combined nitrogen, due to — 
(a) Excess of nitrogen carried off in crops. 
(/ 3 ) Washed away by rain from soil. 
(y) Lost in drainage through subsoil. 
( 8 ) Loss of ammonia diffused into the air. 
It is only necessary to note that various observers have 
shown that in a rotation of crops more nitrogen is carried 
off in the total crops than was contained in the manure, sup- 
posing the latter completely utilised. The examination of 
streams and of drainage-waters gives some idea of the loss 
by superficial and subterranean water : quoting one case 
only, the Rhine and Seine were calculated to carry off about 
200,000 kilograms of nitrates annually. 
With respect to ammonia diffusing into the air ; not all 
the ammonia of the soil is oxydised to nitrates, but some 
forms volatile compounds — e.g. the carbonate. 
(2) Deherain then proceeds to examine the loss of free 
nitrogen. 
It appears that whenever decomposition of organic matter 
occurs, there is, in addition to ammonia, free nitrogen also 
evolved : the chief condition necessary is active oxidation. 
1 Vol. xviii. Ser. 5, 1 Recherches sur l’intervention de l’azote atmospherique dans 
la vegetation,’ p. 147. 
