1882.] 
,4 gricultura l Possibi lities . 
527 
for the community in the ways of political and social agita- 
tion. The attention of this second class may perhaps be 
usefully directed to a certain anomaly which weighs heavily 
both upon the farmer and upon the consumer of agricultural 
produce. It is this : the retail price of manufactured goods 
of all kinds is approximately regulated by the law of supply 
and demand ; but as regards the natural produce of the 
earth, especially articles of food, this is not the case. Prices 
do not fall as the supply increases. A ring of middlemen 
have thrust themselves in between the consumer and the 
producer, and create artificial scarcities even by the destruc- 
tion of perishable-goods. Is this to be still tolerated ? 
Turning now from these introductory considerations we 
come to the main ideas of M. Ville’s work. He maintains 
that four constituents only require to be supplied to arable 
lands in order to maintain, and even increase, their fertility, 
— that is to say, nitrogen, phosphoric acid, potash, and lime. 
He fully admits that plants require also other elements for 
their growth, such as hydrogen, oxygen, carbon, magnesia, 
iron, sulphur, &c. But he maintains that all these bodies 
are supplied in superabundance by the air, the water, and 
the soil, and their special presence in manures is therefore 
needless. The four more important principles he supplies 
in certain specified states. Thus nitrogen he gives by pre- 
ference either as a salt of ammonium, generally the sulphate, 
or as a nitrate of potash or soda. In these states it is at 
once ready for assimilation by the plants, and is not liable 
to be lost by fermentation and evaporation. With nitrogen 
in organic compounds — e.g,, in wool-waste, hair, blood, fish- 
refuse, &c. — the aCtion is not immediate. Decomposition 
must take place before nitrogen in such states is available as 
plant-food, and if such food is immediately needed time is 
lost. Further, during the decomposition of nitrogenous or- 
ganic matters a considerable proportion of the nitrogen — 
according to M. Ville about 30 per cent — escapes in the free 
state, and is lost. 
But whilst our author is at one with all other agricultural 
chemists in holding nitrogen essential for plant-growth, he 
differs from his colleagues by maintaining that leguminous 
plants, peas, beans, and lucerne, can absorb and assimilate 
the free nitrogen of the air. He finds that such crops are 
not appreciably benefitted by ammoniacal manures, and that 
generally speaking it is sufficient if one-half the nitrogen 
which is removed by crops is returned to it in the form of 
fertilisers. He asserts that a crop of lucerne yields per acre 
264 lbs. of nitrogen over and above what can have been 
