Peruvian Guano. 
189 
or a turf-beater. It is extremely difficult, however, by these means 
to reduce them to a sufficiently fine powder. Even grinding under 
a millstone does not answer the purpose, for guano is very apt to 
cake under the stone. It therefore requires to be mixed with 
some material which counteracts this tendency to cake. Gypsum, 
fine ashes, salt, charcoal-dust, and dry soil, are some of the 
materials that have been recommended. Gypsum, however, does 
not prevent the caking ; it therefore is ill suited for the purpose. 
Salt likewise is objectionable ; for it gives the guano a moist 
appearance, and rather increases than diminishes the difficulty. 
Finely-sifted coal or wood ashes, charcoal-dust, and dry soil, 
answer better ; but perhaps the best material for effecting the 
reduction of guano to a fine powder is sharp sand. 
The proper way of proceeding is first to sift off all the fine guano- 
dust, then to mix the hard lumps left in the sieve with about 
twice their bulk of sand, to spread the mixture on an even floor, 
and to pass a heavy roller over it, or to beat down the lumps 
with a wooden mallet. The admixture of sand prevents the 
caking of the guano, and greatly facilitates its reduction to fine 
powder. After the whole has gone through the sieve, salt in the 
proportion of two parts by weight to one of guano may be added 
with great advantage. The moisture imparted to the guano by 
the salt prevents the dusting, which is so great an inconvenience 
in sowing it by hand. Salt in conjunction with guano, more- 
over, has a specific action on vegetation, which is specially bene- 
ficial to corn-crops on light soils. 
Analyses of Guano. 
Notwithstanding that many elaborate and careful analyses 
have been made, some peculiarities in the chemical constitution 
of Peruvian guano have been passed by either unnoticed or have 
not attracted the degree of attention to which they are entitled. In 
order to render more intelligible in what these peculiarities con- 
sist, and how far they affect our endeavours to render guano more 
efficacious, I would invite attention to the following analyses of 
three samples of Peruvian guano of this year's importation. 
Composition of Three Samples of Peruvian Guano. 
18-42 
15-14 
16-56 
'Organic matters and salts of ammonia .. 
52-11 
52-81 
51-70 
riiosphates of lime and magnesia (bone-earth) 
21-99 
20-26 
23-55 
6-37 
10-52 
6-44 
Insoluble siliceous matters (sand) 
1-11 
1-27 
1-75 
100-00 
100-00 
100-00 
15-34 
15-41 
15-13 
18-G2 
18-G9 
18-37 
2-23 
2-48 
1-08 
4-83 
5-36 
2-34 
