200 
Peruvian Guano. 
It is not possible to wash these alkalies completely out 
of guano even where large quantities of boiling water are 
employed. 
7. That by far the greater portion of the nitrogen contained in 
the organic matters of guano is soluble in water, and there- 
fore may be supposed to be present in a readily assimilable 
state for the use of plants. 
On burning, Peruvian guano leaves a perfectly white ash, 
which dissolves in hydrochloric acid without the least effer- 
vescence. The amount of sulphuric acid in this ash is much 
less than in the guano before it is burnt. The three samples, 
in which I found before burning 3'52 per cent., 2"88 per cent., 
and 3*30 per cent, respectively, gave ashes which contained only 
1'29, 1'25, and 1*16 per cent, of sulphuric acid. As guano 
leaves only one-third of its weight, in round numbers, of ash, it 
is evident that by far the greater proportion of sulphuric acid 
which it contains, is dissipated by burning. 
In the next experiment I tried to exhaust Peruvian guano 
completely with water. 
100 grains were boiled repeatedly with large quantities of 
water, and the insoluble portion was washed upon a filter with 
distilled water for more than five days. Even after that time a 
little was dissolved, but as the washings then contained only 
a trace the exhaustion by water was discontinued, the insoluble 
matter collected on a weighed filter, dried at 210°, weighed, and 
then burned. The insoluble matter was analysed as before. 
The whole of the solution was exaporated to dryness, and the 
residue, after drying at 212°, weighed and analysed. 
During the evaporation of the large quantity of fluid em- 
ployed in exhausting the guano, ammonia was constantly given off, 
and as the complete evaporation and drying of the residue occupied 
nearly a week, a large proportion of uric and other nitrogenised 
compounds was destroyed and dissipated in the form of carbonate 
of ammonia. It will be seen by the subjoined analysis that no 
less than 33^ per cent, of organic matter were destroyed in this 
way. 
The guano analysed in the usual way, that is without exhaust- 
ing it first with water, produced the following results: — 
Moisture • 15-90 
Organic matter and ammoniacal salts 53 - 73 
Phosphates of lime and magnesia (bone-earth) .. 2±07 
Alkaline salts 7*17 
Insoluble siliceous matter 1'13 
100-00 
""Containing nitrogen 15-74 
Ejual to ammonia l'J-11 
