144 NOTE ON HUAN ISLAND GUANO. 
The amount of carbon dioxide evolved from the ash of the 
guano was also found to be slightly aati than that from the 
guano itself, showing the presence of an organic calcium salt. 
Thus, three samples gave as the mean of aovaral closely approxi- 
mating determinations :— 
No.1. No.2. No. 3. 
pee ear itins in the ash calculated) yn 4.54 450 
Caction dioxide in the raw guano ne a, tar ee 
The limited quantity of material at command has prevented 
further research on this point for the present. 
As the carbonate of ammonia method failed, portions of the 
guano were mixed with a little hot water, transferre d to a filter 
solution was ey Lech only, and was treated with oxalate of 
ammonium and acetic acid to remove a trace of calcium, and the 
phosphoric acid determined as magnesium pyrophos hate with 
the following results from different samples, the first three being 
from one island and the other two from another, the total 
hosphorie acid and ase to of calcium calculated from the 
carbon ce being also 
otal Ph oe Soluble Phosphoric Acid. Calcium Carbonate, 
5 
No. 1 29°96 018 9°47 
2 31°68 0°53 2°88 
3 3157 0-44 2°54 
32°14 0°42 2°47 
34° 0°63 
2:29 
It appears as if the organic matter protected the calcium 
carbonate to some extent from the = pr the phosphoric acid, 
so that it may be pang orks and thus occasional showers of rain 
would carry it down the lower ayaa. c of the guano beds 
there co sagra the carbonate into phosphate. 
pct laye guano Foon through this acid stage in the 
gradual iscsi se the iaecgie matter and passage from a 
mixture contai ‘ganic matter a small quantity ¢ of 
e t 
potty. confined to a thin layer at one seine with which otha 
ers had been mixed in the samples examin 
