532 
A gricultural Possibilities. 
[September, 
carbonic acid, is able to assimilate. As an instance, on 
treating the soil of his experimental field at Vincennes with 
hydrochloric acid, the author found phosphoric acid in the 
proportion of 1581 lbs. per acre. On lixiviating with water 
the quantity obtained was only 25 lbs., but if beet-root is 
cultivated upon this land for three consecutive years it ex- 
tracts from the soil 132 lbs. of phosphoric acid ! Hence the 
author recommends, as a more practical and decisive method 
of learning the condition of the soil, the systematic forma- 
tion and use of trial plots. 
It is in these days something remarkable that M. Ville 
proposes no method of utilising the immense amount of 
plant-food which, in the form of human excreta, is daily 
finding its way into the rivers and the sea. He seems to 
consider the supply of nitrogen, of phosphates, and of pot- 
ash practically unlimited. I cannot, however, help remarking 
that the problem of converting the free nitrogen of the air 
on commercial terms into ammonia, though possibly soluble, 
has not yet been solved. It is hardly safe to discount the 
results of a merely probable invention. 
We have frequent references to irrigation as an anciently 
known means of fertilising the soil ; but these passages deal 
merely with the flooding or inundation of water-meadows 
during the dead season of vegetation, and have nothing in 
common with the modern scheme of sewage irrigation ap- 
plied continuously. 
M. Ville, like many of his countrymen, is not a little exer- 
cised on a subject intimately linked with the national supply 
of food. France, more perhaps than any other country, has 
sought to keep down superfluous mouths ; she has, so to 
speak, capitalised the funds which would have been required 
for bringing up a more numerous population, and she is now 
far from satisfied with the results. The faCt remains that a 
Malthusian nation, or a Malthusian class in a nation, must 
simply efface itself unless similar principles were universally 
adopted. All schemes proposed by man to stamp out the 
struggle for existence in his own species seem doomed to 
failure. 
Setting aside M. Ville’s questionable views on the assimi- 
lation of free nitrogen and on the universal necessity for 
gypsum, his teachings must be regarded as of the highest 
value both in his own country and on this side the Channel. 
