On the Analysis of Guano. 
295 
c, the third portion, has a certain measure of a definite solution of 
ferric nitrate mixed with it, and then ammonia in excess. From the 
weight of the precipitated subphosphate of iron after ignition, the known 
amount of oxide used being deducted, the quantity of phosphoric acid in 
the soluble portion of the guano becomes known. 
rf, the three above portions are now mixed, freed by a few drops of 
dilute sulphuric and hydrochloric acids from any barytes and silver left 
in them, and then tested by nitrate of lime for oxalate of ammonia. 
The quantity of oxalate of lime obtained determines that point. 
6. The last liquor filtered, being freed from any residuary particles 
of lime by oxalate of ammonia, is evaporated to dryness and ignited, to 
obtain the fixed alkaline matter. This being weighed, is then dissolved 
in a little water, neutralized with acid, and treated with soda-chloride of 
platinum. From the quantity of potash-chloride of platinum which 
precipitates, after being filtered, dried, and weighed, the amount of 
po:ash present is deducted; the rest is soda. These bases may be 
assigned to the sulphuric, hydrochloric and phosphoric acids, in propor- 
tions corresponding to their respective affinities. 
7. The proportion of organic matter in the above solution of guano is 
determraed directly by evaporating a certain portion of it to dryness, and 
igniting. The loss of weight, minus the ammonia and oxalic acid, 
represents the amount of organic matter. 
8. A second portion of a solution of the guano is evaporated to dry- 
ness by a gentle steam-heat, weighed, inclosed in a stout well-closed 
phial along with alcohol of 0"825, and heated to 212'. A(ter cooling, 
the alcoholic solution is decanted or filtered clear, evaporated to dryness 
by a gentle heat, and weighed. This is urea, which may be tested by 
its conversion into carbonate of ammonia, when heated in a test-tube or 
smnll retort. In this way I have obtained from Bolivian guano 5 per 
cent, of urea : a certain proof of its entire soundness. 
9. Analysis of the insoluble matter. — One-third of it is digested with 
heat in abundance of borax-water, containing -^i-g- of the salr, filtered, 
and the filter dried by a s:eam-heat. The lois of weight indicates the 
amount of uric acid, which is verified by supersaturating the filtrate 
with acetic or hydrochloric acid, thus precipitating the uric acid, throw- 
ing it upon a filter, drying, and weighing it. This weight should nearly 
agree with the above loss of weight, the small difference being due to 
soluble organic matter, sometimes called geine and ulmic acid. The 
uric acid is endenced, — 1, by its specific gravity, which 1 find to be 
only 1-25, as also that of the urate of ammonia; 2, by its affording 
fine purple murexide when heated in a capsule along with nitric acid, 
and then exposed to the vapour of ammonia from a feather held over 
it ; 3, by its dissipation when heated, without emitting an empyreumatic 
odour. 
10. Another third of the solid matter is distilled along with half its 
weight of slaked lime and ten times its weight of water, in the apparatus 
already described, and the ammonia obtained from it estimated. 
11. The remaining thiro having been ignited, is dissolved with a 
gentle heat in weak hydrochloric acid, and the remaining silica and 
alumina washed on a filter, dried, and weighed. To the hydrochloric so- 
lution, dilute sulphuric acid is added, and the mixture is heated till all the 
