350 Annual Report of the Consulting Chemist. 
of moisture is always more or less lumpy, and becomes pasty when 
the attempt is made to reduce it to powder. The difficulty of 
reducing such guano into a fine and powdery state, in which it 
can be readily and uniformly distributed upon the land, is much 
enhanced by the circumstance that some of the lumps, not dis- 
similar in appearance to dark-coloured wet clay, are as damp and 
unctuous as newly made Cheshire cheese ; and others, which may 
be readily mistaken for stones, are so hard that they can onlv be 
broken and reduced to powder by means which are not at the 
command of the farmer. It may at first sight appear a simple 
matter to reduce to powder a material such as damp and lumpy 
Guanape guano ; but it is a far more difficult task than it may 
appear to persons who have not made the attempt. In fact, the 
farmer cannot do this properly himself, and I have therefore advo- 
cated for years past the propriety of treating wet Peruvian guano 
with sulphuric acid, and preparing the sulphated guano into a 
<lrv powder. 
In consideration of the difficulties which at present exist in 
the way of supplying Peruvian guano of a uniform composition 
and in a dry and fine condition, the Peruvian Government have 
recently consented that the present contractors for the sale of 
Peruvian guano in Europe might treat guano with sulphuric 
acid. Dissolved Peruvian guano is now prepared under the 
control of the Peruvian Government agents, and sold by them 
in a dry and finely powdered condition, with a uniform compo- 
sition guaranteed by analysis. 
All the samples of dissolved Peruvian guano which were sent 
for analysis by members of the Royal Agricultural Society in the 
course of last season were found fully up to the mark, and in an 
excellent mechanical condition. 
It has been alleged that the phosphates in Peruvian guano 
exist in it in a sufficiently available condition to meet the require- 
ments of the farmer, and that for this reason the manufacture of 
dissolved guano is a great mistake ; and undoubtedly if Peruvian 
guano at present were as dry and easily reduced to^ powder as 
the former and now exhausted supplies from the Chincha Islands 
there would be no necessity of treating guano with sulphuric acid 
The object of the manufacture of dissolved guano is not 
merely to render the ordinary insoluble guano-phosphates soluble 
but to prepare the manure in a dry and powdery condition and 
of a uniform composition. This object is best accomplished by 
treating raw guano with about 20 per cent, of oil of vitriol ; for 
in rendering the insoluble phosphate of lime in guano sokible, a 
certain amount of sulpliate of lime is produced, which, combininjjf 
chemically with a fixed quantity of water, acts as an efficielft 
drying material ; whilst at the same time the acid neutralises th 
