OXALIC ACID IN PERUVIAN GUANO. 
295 
with guano yielded an abundant crop, while the addition, to 
a part of the same soil, at the same time, and for the same 
crop, of a quantity of ammoniacal salts corresponding exactly, 
in richness with nitrogen, to the guano employed, had scarcely 
any effect on the crop. 
If, in the first instance, guano owes its fertilising properties 
to the nitrogen it contains, it is difficult to comprehend why, 
in the second instance, the same quantity of nitrogen, added 
to the soil in its most active form, should have no influence 
on the crop. The cause of the energetic action of guano 
must then be sought in its other constituents. If from these 
we except uric acid, the influence of which on vegetation is 
almost completely unknown, there remain only earthy phos¬ 
phates and alkalies, which, existing simultaneously with am¬ 
moniacal salts, might communicate to guano its active pro¬ 
perties. 
According to M. Liebig, various reasons prevent the ac¬ 
ceptance of this conclusion. Phosphate of lime is, with am¬ 
moniacal salts, the predominating element of Peruvian guano, 
which contains 32 to 36 per cent, of it. A quantity of phos¬ 
phate (powdered bones), four, six, or even eight times larger 
than that contained in guano, is very far from producing the 
effect of the natural manure : its fertilising action is frequently 
increased by the addition of ammoniacal salts, but the results 
fall far short of those produced by guano containing phos¬ 
phates in the same proportion. The principal difference to 
be remarked between these two manures consists in the 
length of time each takes to manifest its action,—a point 
which has hitherto remained unexplained. The influence of 
guano is apparent the first year, often even after a few weeks, 
and goes on diminishing year by year; the powdered bones, 
on the contrary, act feebly during the first season, but after¬ 
wards their effect increases. 
These facts once established, we will adduce M, Liebig’s 
experiments, which tend to prove that guano owes its rapid 
action to the presence of oxalic acid. 
Various kinds of guano contain very varying quantities of 
oxalic acid,—another proof that the composition of guano is 
not constant. Certain anal 3 ’^sis, not indeed sufficiently 
numerous to lead to a positive conclusion, seem to prove 
that the quantity of oxalic acid contained in a sample of 
guano is in inverse proportion to the weight of uric acid it 
contains; that is to say, that the guanos rich in uric acid are 
generally poor in oxalic acid. 
If Peruvian guano is moistened with either cold or boiling- 
water, and filtered immediately after, the liquid furnishes, by 
