Peruvian Guano. 
201 
Nearly exhausted with water the same guano furnished the 
following proportions of soluble and insoluble matters: — 
Percentage of soluble portion 74/89 
Percentage of insoluble portion 25-11 
Thus nearly three-fourths of the weight of the guano passed 
into solution, and one-fourth only was left behind insoluble. 
This portion we shall see presently consisted almost entirely of 
insoluble phosphates and insoluble siliceous matter. 
The analysis of the soluble and the insoluble part gave the 
following results : — 
Part soluble in water 74-89 
Consisting of: — 
Moisture 15-90 
Tribasic phosphate of lime 2 - 92 
Alkaline salts 6*91 
Containing phosphoric acid ',. 1'28 
Equal to tribasic phosphate of lime (2'77) 
Soluble organic matters (left in dried residue on evapo-1 j^.^o 
rating the watery solution) / 
Soluble organic matters (decomposed and resolved chiefly) 33.4Q 
into ammonia compounds during evaporation) .. ../ 
Part insoluble in water 25-11 
Consisting of: — 
Insoluble phosphates 19'82 
Oxalate of lime '56 
Potash and soda .. '77 
Insoluble siliceous matter (sand) P36 
Insoluble organic matter 2*60 
100-00 
It is remarkable that tire insoluble portion, notwithstanding 
that an immense quantity of water was passed through it, still 
contained some potash and soda, which it seems to have a great 
power of retaining. The phosphate of lime, which consti- 
tutes so large a part of the insoluble residuum, seems to have 
the power of forming with alkalies a chemical union which is 
broken up with great difficulty, and only very gradually, by boil- 
ing water. 
The larger amount of bone-earth in this watery solution is 
accounted for by the large quantity of water used in the experi- 
ment. We have in this a direct proof that the insoluble phos- 
phates in guano are rendered soluble by degrees by a sufficiently 
large quantity of water. 
Combined Action of Sulphate and Oxalate of Ammonia. 
Peruvian guano we have seen contains both sulphate and 
oxalate of ammonia. Liebig has shown that these two salts have 
an important function in rendering the insoluble phosphates 
