30G 
On the Anali/sis of Guano. 
Voelckel, in his analysis of guano, states 7 per cent, of oxalate of 
lime ; a result quite at variance with all my experience, for I have never 
found so much as 2 per cent, of carbonate of lime in the washed and 
gently ignited insoluble matter ; whereas, according to Bartels and 
Voelckel, from 10 to 5 per cent, of carbonate should be obtained, as the 
equivalents of the proportions of the oxalate assigned by them. 
All these analyses are defective, moreover, in not showing the total 
quantity of ammonia which the guano is capable of giving out in the 
soil ; and, since it appears that the freshest guano abounds most in what 
I have called potential ammonia, it must possess, of consequence, the 
greatest fertilizing virtue. 
A sample of decayed dark-brown moist guano, from Chile, being ex- 
amined, as above described, for oxalate of ammonia, was found to con- 
tain none whatever ; and it contained less than 1 per cent, of uric acid. 
An article offered to the public, by advertisement, as Peruvian guano, 
was lately sent to me for analysis. I found it to be a spurious composi- 
tion : it consisted of — 
1. Common salt . . . . . . 31'5 
2. Common siliceous sand .... 2S'0 
3. Sulphate of iron or copperas . . . 5*2 
4. Phosphate of lime . . . . . 4'0, with 
5. Organic matter from bad guano (to give it smell) 23 '3 
6. Moisture . . . . . . . 8*0 
100-0 
Genuine guano, when burned upon a red-hot shovel, leaves a white 
ash of phosphate of lime and magnesia ; whereas this factitious sub- 
stance left a black fused mass of sea-salt, copperas, and sand. The 
specific gravity of good fresh guano is seldom more than 1*66, water 
being 1"00; whereas that of the said substance was so high as 2" 17 ; 
produced by the salt, sand, and copperas. 
ERRATUM. 
At page 45 — see Art. V. in the points for cows — for 4 points read 3 — wLich correc' 
tion accounts for SO points, or perlVction in milch cows. 
