» 
Peruvian Guano. 191 
in greater abundance than in dry and sound samples. In good 
samples, which have an aromatic rather than pungent smell, I 
find invariably a large proportion of uric and little oxalic acid, 
and in inferior, dark, strong-smelling damaged samples, com- 
paratively speaking, little uric and much oxalic acid ; therefore a 
Large amount of oxalic acid in guano indicates inferior quality. 
The oxalic acid, however, as we shall see hereafter, plays an 
important part in rendering the insoluble phosphatic constituents 
soluble. 
Ready-formed Ammonia in Guano. 
In a scientific point of view, the determination of ready- 
formed ammonia in guano is of some interest. In a practical 
point of view, it likewise appeared to me desirable to ascer- 
tain whether or not guano contains any free or, more properly 
speaking, volatile carbonate of ammonia. I therefore deter- 
mined in the preceding samples both the amount of free 
ammonia and that present in the shape of ammoniacal salts. 
For this purpose 100 grains of each sample were introduced 
into a glass retort, and mixed with 4 ozs. of distilled water. The 
retort was connected air-tight with a glass receiver, to which was 
attached the bulb apparatus, used in nitrogen combustion. Both 
the glass receiver and bulb apparatus contained a measured 
quantity of sulphuric acid of known strength for the reception of 
the ammonia given off during the process of distillation. The 
contents of the retort were nearly distilled to dryness, and bv' 
this means the free or volatile carbonate of ammonia was dis- 
tilled over with water only, and received into sulphuric acid. 
It is hardly necessary to observe that a portion of the acid 
becomes neutralised by the ammonia, and that by employing a 
fixed quantity of sulphuric acid, and a standard solution of 
caustic soda, the exact amount of ammonia given off during the 
distillation can be readily determined by the well known alkali- 
metrical process. 
The result was that the 3 samples furnished : — - 
No. I. No. 2. No. 3. 
Ammonia 1-13 1-31 1-32 
It thus appears that the proportion of free ammonia in these 3 
samples of good Peruvian guano was little above. 1 per cent. 
The preceding figures express the amount of caustic or free 
ammonia contained in the vapours that were received in the acid 
during the process of distillation. Guano, however, like all 
other putrefying nitrogenous substances, does not furnish ammonia 
free or caustic, but as a carbonate ; this carbonate is often in 
common life miscalled free ammonia, in consequence of its being 
volatile and having the same smell. 
