290 
On the Analysis of Guano. 
at this preference, when -we learn that in the valley of Chancay, about 
40 miles distant from Lima, the soil produces, when farmed with irriga- 
tion in the natural way, a return upon maize of only 15 for 1 ; whereas, 
with the aid of guano, it produces 300 fur 1 ! Hence the Peruvian pro- 
vcrh : — Huano, though no saint, works many miracles. 
In the ]iamphlet recently published by Messrs. Gibbs and Myers, 
entitled "PeruviMU and Bolivian Guano; its nature, properties, and 
^e^ults," we have a very in eresting view of the best established facts 
with regard to its operat.on and effects upon every variety of soil, and in 
every variety of circumstance, as ascertained by the most intelligent 
agriculturists of the United Kingdom. The general conclusion that may 
be fairly deduced from the whole evidence is, that good guano will, 
under judicious application, increase the crops of grain, turnips, potatoes, 
and grass by about 33 per cent ; and with its present price of 10/. per 
ton, at a cost considerably under the average cost of all other manures, 
whether farm-yard dung and composts, or artificial com).ounds. Guano 
is, moreover, peculiarly adapted to horticultural and floricultural im- 
provement, by its relative cleanliness and facility of application. 
The following observations upon guano, bv Dr. Von Martins, of 
Munich, addressed to the Aoricuitural Society of Bavaria, deserve atten- 
tion : — " Among animal manures," says he, " it clearly claims the first 
place. It is uncommonly rich in ammoniacal salts, which act very 
favourably on vegetation. The ease with which these salts are decom- 
posed, and exhale their ammonia into the air, is by him assigiied as the 
reason why plants manured with guano generally present early in the 
morning accumulations of dew on the points of their leaves. The guano 
absorbs the atmospheric vapour, as well as carbonic acid; whereby it 
becomes so valuable a manure in dry barren regions. If we compare 
guano with other excrementitious manures, we shall find it far preferable 
to those afforded by man or other mammalia, which do not generally 
contain more than 20 per cent, of food that can be appropriated by 
plants. It is therefore five times better than night-soil, and also very 
superior to the French poudrette which (being dried night-soil) loses, 
through putrefaction and evaporation, the greater proportion of its am- 
monial elements. In birds, the excretions both of the kidneys and in- 
testines are contained in the cloaca ; whereby the volatile elements of the 
former get combined with the more fixed components of the latter." 
The guano is also a richer manure, on account of its being produced 
by sea-fowl, which live entirely on fish, without admixture of vegetable 
matter. The exposure also of the guano as soon as deposited to the heat 
of a tropical sun, in a rainless climate, prevents the components from fer- 
menting, and ynummijies them, so to speak, immediately into a concrete 
siibstance not susceptible of decomposition till it gets moisture ; whereas 
the dung of our dove-cots suflfers a considerable loss by exposure to our 
humid atmosphere. But in their action on vegetation, and in their 
chemical composition, these two bird excrements are analogous. Davy 
found in fresli dove-cot manure 23 parts in 100 soluble in water, which 
yielded abundance of carbonate of ammonia by distillation, and left car- 
bonaceous matter, saline matter, principally common salt, and carbonate 
of lime as a residuum. Pigeons' dung readily ferments, but after 
fermenution afforded only 8 per cent, of soluble matter, which gave 
