208 
Peruvian Guano. 
Composition of Guano dried with 20 per cent, of Oil of Vitriol 
(SO* HO), 
Water driven off at 212° Fahr 5-44 \ o 
Bi-phosphate of lime 5-36 "% 
Equal to tribasic phosphate of lime (8"37) "3 ro 
Sulphate of lime 7*31 \ <a L L 
Alkaline salts 10-54 [ $g 
Containing phosphoric acid ' .. .. (6 - G8) g> 
Equal to tribasic phosphate of lime (14-47) " g 
^Soluble organic matter and salts of ammonia .. .. 44*59 ) Ph 
t Insoluble organic matter 9'50 ~\ to a .~ 
Insoluble phosphates 3-06 I ■§ •§ *j-g> 
Oxalate of lime 12-97 
Insoluble siliceous matter 1-23 
OJ r-H 
100-00 
*Containing nitrogen 3'01 
Equal to ammonia 3 - 65 
•(•Containing nitrogen .' 10-59 
Equal to ammonia .. 12-86 
In all the four trials, with 5, 10, 15, and 20 per cent, of acid, 
the amount of soluble phosphoric acid in the alkalies and of 
oxalate of lime in the part insoluble in water differed but incon- 
siderably. 
By the agency of oxalic acid, naturally present in the guano, 
assisted by only 5 per cent, of sulphuric acid, a very large pro- 
portion of the insoluble phosphates are thus rendered soluble 
in water ; and the larger quantities of acid were expended in the 
foregoing experiments with far less economical advantage than 
the first 5 per cent. 
On the strength of these experiments, I would strongly recom- 
mend the addition of about 5 per cent, of oil of vitriol to guano 
as a cheap and ready means of greatly increasing its efficacy. 
The expense of so small a quantity of acid is too trifling to require 
a moment's consideration. Some difficulty, however, 1 anticipate 
may be felt in incorporating the acid uniformly with the guano. 
As the proportion of acid to that of the guano is very small, an inti- 
mate mixture cannot be effected by simply pouring the acid upon 
the latter, nor is it desirable to use the acid in a concentrated 
state. 
Practical Directions. 
I would therefore suggest the following plan : — In the first 
place, dilute the oil of vitriol with about an equal bulk of 
water, and then sprinkle the dilute acid over dry sawdust, or, 
if that cannot be had, over ground gypsum or sand. Dry saw- 
dust takes up a great deal of liquid without appearing particu- 
larly wet. Gypsum or sand do not take up so much liquid, and 
