34 CHEMICAL DEPARTMENT. 



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

 which are insoluble and of low mauurial value, otherwise it resembles high- 

 class Peruvian guano. 



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

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

 present. 



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

 and offal 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 fish-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. 



Frey-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 

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

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

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

 portion of potash. It should lie mixed with other and quicker manures, 

 such as superphosphate and a little nitrate. 



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

 genous matter. Phosphates range from 4-1 to 55 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. The 

 higher the phosphates the lower the ammonia, and vice versa. There is 

 usually 3 per cent, or more of oil in bones, and this may retard 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 

 l^ressure for the extraction of glue or gelatine. The residue contains from 

 5G to 65 per cent, phosphates and from 1 to 2 per cent, ammonia. It is 

 white coloured and friable, and can be crushed with the hand. It is able 

 to be, and ought to be, ground to a fine flour. Owing to this latter character, 

 it is the most active form of bone manure. 



Pure Dissolved Bones. — Bones dissolved in sulphuric acid and dried with 

 bone ash or bone char,' or' other bone material. It contains usually less than 

 20 per cent, soluble phosphate, about 10 per cent, or upwards of insoluble 

 phosphate, and yields from ^h to 3i per cent, ammonia. 



Dissolved Bones. — A conventional name applied to compound manures, 

 consisting of any mixture of phosphatic and nitrogenous materials which 

 can be dissolved, with (or without) an admixture of bone, so as to j^roduce 

 a manure containing from 15 to 30 per cent, soluljle phosphates, and 

 from 1 to 3 per cent, ammonia. Dissolved bones has become a general 

 name for a dissolved compound manure. 



Pure Vitriolated Bones. — Bones which have been moistened with sul- 

 phuric acid, and thereafter allowed to heat in large heaps for a long time. 

 Good samples contain from 6 to 12 per cent, sohtble phosphate, with from 

 30 to 40 per cent, insoluble phosphate, and yield from 3 to 4 per cent, 

 ammonia. It should consist of nothing but bones and sulphuric acid. 



