On Pliosjihatic Guanos. 447 
following partial ones may be quoted as fairly representing the 
average contents of the present imports in phosphate of lime : — 
General Compositiox of Mejillones Guano. 
No. 1. 
No. 2. 
No. 3. 
No. 4. 
No. 6. No. 6. 
1 
^Moisture and organic matter 
Magnesia, carbonic acid, j 
sulphuric acid, alkaline) 
"Insoluble siliceous matter .. 
• Equal to tribasic phos-'l 
phate of lime . . . . / 
14-46 
32-35 
37-56 
12-54 
3-09 
15-01 
34-71 
31 '75 
13-63 
4-90 
13- 87 
33-79 
30-61 
14- 30 
7-43 
15-80 
34-12 
36-41 
11-38 
2-29 
15-01 
33- 54 
34- 07 
10-93 
6-45 
16-62 
31-84 
34-97 
11-73 
4-84 
100-00 
100-00 
100-00 100-00 
100-00 
100-00 
70-62 
75-77 
73-76* 
74-48 
73-22 
69-51 
Although Mejillones guano may be applied with more or less 
advantage to the land without any previous preparation, except 
sifting and crushing the lumpy portion into a fine powder, it 
is more economical to treat the guano with sulphuric acid, and 
to convert the greater portion of the insoluble phosphate of 
lime which it contains into soluble phosphate. It is readily 
acted upon by dilute sulphuric acid, and is a most valuable 
material for producing manures containing a high percentage 
of soluble phosphate of lime. It has been alleged that Mejil- 
lones guano, when treated with sulphuric acid, does not readily 
! fall to a fine and dry powder, but is apt to remain permanently 
in a wet and rather pasty condition. This, no doubt, may happen, 
and it generally takes place, if the guano, as imported, is treated 
with weak acid. Not unfrequently it arrives in Europe in a 
somewhat damp condition, and if dissolved in that state in 
weak chamber-acid, the resulting soluble guano appears more 
or less moist, according to the percentage of moisture in the 
raw guano, and the extent to which it has been rendered soluble 
by a larger or smaller addition of weak acid. But this objec- 
tion to its fitness for the production of manures rich in soluble 
phosphate is not a valid one ; for Mejillones guano, thoroughly 
dried on a heated floor, and then passed through a fine sieve, 
can be treated with an amount of sulphuric acid large enough 
to render nearly the whole of the insoluble phosphate of lime 
soluble, without danger of turning out damp and pasty. In 
I this way, dissolved Mejillones guano, containing from 40 to 43 
per cent, of soluble phosphate of lime, may be obtained in a 
sufficiently dry and powdery condition to go readily through 
I a manure-drill. 
ill 
