204 
Peruvian Guano. 
before us the guano sustained a loss of 3'58 per cent, of nitrogen, 
equal to 4"34 per cent, of ammonia, in the short period of three 
weeks, and as the loss increases with the length of time during 
which it is kept in a wet and fermenting condition, it is hoped 
no further argument is required to induce agriculturists to store 
Peruvian guano in a perfectly dry place, and to take care either 
to apply damaged guano at once to the land or, if that may not 
be done, to dry it. 
The dissipation of organic matter necessarily raised the total 
percentage of phosphates, which rose from 25 - 05 per cent, of 
soluble and insoluble phosphates, calculated as tribasic phosphate 
of lime, to 31 - 07 per cent., being an increase of 6 per cent. 
By far the larger proportion of the increase in phosphates, it 
will be seen, makes its appearance in the watery solution of the 
fermented guano. That the insoluble phosphates are rendered 
soluble, at least in part, through the joint action of sulphate and 
oxalate of ammonia on the earthy phosphates, appears evidently 
from the considerable proportion (6 per cent.) of oxalate of lime 
which was found in the fermented sample. 
Moistening guano with water previous to use, although it 
increases the solubility of the phosphates, cannot be recom- 
mended, because this effect is attended with a loss of a great deal 
of ammonia. 
Use of Sulphuric Acid. 
The insoluble phosphates may, however, be rendered soluble 
more perfectly by a little sulphuric acid without any loss of 
costly nitrogen ; a quantity too small to give an acid reaction to 
the guano producing a most decidedly beneficial effect upon the 
insoluble phosphates. 
Treated with only- 5 per cent, of oil of vitriol, guano yields, 
as we shall see presently, quite half its amount of phosphoric acid 
to water ; whilst without such treatment scarcely one-fifth of its 
phosphoric acid occurs in a soluble state. 
The peculiar action of sulphuric acid upon guano is due to 
the presence of oxalate of ammonia and to the sulphate of 
ammonia which is then formed. With a view of studying 
experimentally the effect produced by very moderate additions of 
oil of vitriol, and of ascertaining in what proportions it should 
be added, I tried the following experiments : — 
Four small quantities of good Peruvian guano were severally 
mixed with 5, 10, 15, and 20 per cent, of oil of vitriol (S 0 3 , H O), 
and the mixture dried on the top of a waterbath, after which a 
weighed quantity was very nearly exhausted with distilled water. 
The soluble and insoluble portions were then in each case analysed 
separately. The guano employed in these four experiments con- 
tained in 100 parts — 
