300 Annual Report of the Consulting Chemist. 
preceding year. All the samples sent for analysis were found 
up to the guarantee, and in a uniformly dry and finely powdered 
condition. As long as the Peruvian Government agents sell 
dissolved guano in a first-class dry and powdery state, equal to 
their guarantee, and at a fair price in comparison with the price 
of compound ammoniacal manures, I believe its consumption will 
increase from year to year. 
Mixtures of superphosphate with nitrate of soda, as is well 
known, have been used with much advantage for cereal crops, 
especially for barley. There can be no doubt that, at the present 
unusually low price of nitrate of soda, such mixtures are cheaper 
than raw or dissolved Peruvian guano. It has to be borne in 
mind, however, that nitrate of soda is not retained by soils, like 
ammoniacal salts or nitrogenous organic matters ; and for this 
reason it should not be applied to the land in autumn. It is not 
always desirable to delay the application of nitrogenous top- 
dressings to cereal crops until the spring. Hence good use, it 
appears to me, will continue to be made of Peruvian guano upon 
land and for crops which are best manured in autumn or during 
the winter months, whilst nitrate of soda is best applied to soils 
upon which cereals receive the greatest amount of benefit from 
the use of readily available nitrogen in spring top-dressings. 
On naturally fertile clay-soils, and on heavy land in a fairly 
good agricultural condition, I believe nitrate of soda will be found 
a more economical application for cereal crops than Peruvian 
guano or ammoniacal top-dressings ; but there are unquestionably 
a good many soils upon which the use of nitrate of soda is more 
or less hazardous. Very poor light soils are not only deficient 
in most of the elements of fertility which are required for the 
healthy and luxuriant growth of crops, but they also do not 
possess the power of absorbing and retaining nitrogenous ma- 
nuring matters in the same degree as the heavier and better 
kinds of land. 
In wet seasons nitrate of soda, when applied to light sandy 
soils, runs greater risk of being washed into the subsoil or of 
being carried off into the drains than ammoniacal salts or nitro- 
genous organic matters, or mixtures of both. It is safer,^there- 
fore, to apply upon such soils manures which, like farmyard- 
manure or Peruvian guano, have a far more complex composition 
than mixtures of superphosphate with nitrate of soda. In farm- 
yard-manure and in guano we find not only soluble phosphates 
and nitrogen in one state of combination, but they also contain 
a number of saline mineral matters and a variety of organic 
compounds which do not occur in simple mixtures of superphos- 
phate and nitrate of soda. 
Thus Peruvian guano contains potash in appreciable quantities 
