22 CHEMICAL DEPARTMENT. 



Peruvian Guano. — A general manure formed of the excrements of fish- 

 eating birds, and containing nitrogenous compounds, phosphates, and 

 potash. 



High-class Peruvian guano is rich in nitrogenous matter, a large propor- 

 tion of which is soluble. As now imported, it is capable of yielding from 

 8 to 12 per cent, ammonia, part of which is derived from ammonia salts, 

 and part (less than 1 per cent.) from nitrates. Phosphates are low, seldom 

 exceeding 30 per cent., but from one-quarter to one-half of the phosphates 

 is soluble. The amount of potash is small, usually from 3 to 5 per cent. 



Low-class Peruvian guano, as now imported, is poor in nitrogenous matter, 

 yielding only from 3 to 5 per cent, ammonia. The phosphates are corre- 

 spondingly high, viz., from 30 to 50 per cent., but the proportion of soluble 

 phosphate is much smaller than in high-class Peruvian guano. Potash 

 occurs to a very small extent, viz., about 1 to 3 per cent. 



Low-class guanos are formed from high-class guanos, by the washing out 

 of soluble constituents Ijy rain, &c., and their composition varies greatly 

 according to the amount of washing they have undergone. 



Genuine Peruvian guano frequently contains a large proportion of stony 

 insoluble matter. 



Ichaboe Guano. — A general manure, but of recent formation. It is very 

 rich in nitrogenous matter, which yields from 10 to 16 per cent, of am- 

 monia, but a large part of the nitrogenous matter is in the form of feathers, 

 which are insoluble and of low manurial value. 



The total phosphates vary from 18 to 30 per cent,, of which from a fourth 

 to a half is usually soluble. There is seldom more than 2 per cent, potash 

 present. 



Fish Guano. — Derived from fish-curing yards, and consisting of the heads 

 and off'al of fish, dried and ground. Properly speaking, it is not a guano. 

 The name guano is properly applied only to the dung of birds. 



High-class fish guano contains nitrogenous matter, yielding from 10 to 12 

 per cent, of ammonia, but it is in the form of insoluble albuminous com- 

 pounds, which only very slowly decompose and become available as plant 

 food. The phosphates range from 18 to 30 per cent, and are all insoluble. 



Low-class fish guanos are substances like the preceding, but containing less 

 nitrogenous matter and more phosphates. They are simply bone manures, 

 with somewhat more ammonia and less phosphate than ordinary bone meal, 

 and having no real resemblance to a guano. 



Fish guanos are usually impregnated with fish oil, which detracts from 

 the value of the manure. The oil varies from 3 to 10 per cent. 



Fre 7 Bentos Guano. — The dried and ground residue and debris of animals 

 after the extraction of " Liebig's Extract." It is not a guano. It contains 

 nitrugenous matter and phosphates, both of which are insoluble and slow 

 in their action as manures. It varies in composition, jdelding from 6 to 

 12 per cent, ammonia, from 16 to 35 per cent, phosphates, and a small pro- 

 portion of potash. 



Bone Meal. — Chiefly a phosphatic manure, but containing also nitro- 

 genous matter. Phosphates range from 44 to 53 per cent, according to the 

 purity of the bones, and are insoluble. The nitrogenous matter is capable 

 of yielding from 4 to 5 per cent, ammonia, and is also insoluble. There is 

 usually 3 per cent, or more of oil in bones, and this retards its action as a 

 manure. The finer ground it is the more speedy is its action. 



Bone Dust.— A coarser ground bone than the preceding. 



Crushed Bones. — Still coarser ground. 



Steamed Bone Flour. — Bones which have been subjected to steam at high 

 pressure for the extraction of glue or gelatnie. The residue contains from 

 56 to 65 per cent, phosphates and from 1 to 2 per cent, ammonia. It is 

 white coloured and friable, and can be crushtd ^vith the hand. It is able 



