CHEMICAL DEPARTMENT. 23 



to be, and ouglit 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 cuntains usually less than 

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

 phosphate, and yields from 2^ to 3^ per cent, ammonia. 



Dissolved Bones. — A conventional name applied to compound manures 

 consisting of nay kind of mixture of phosphutic and nitrogenous materials 

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

 produce a manure containing from 15 to 30 per cent, soluble pho.sphates, 

 and from 1 to 3 per cent, ammonia. 



Vitriolated Bones. — Bones which have been moistened -uath sulphuric 

 acid, and theiealter allowed to heat in large heaps for a long time. Good 

 samples contain from 6 to 12 per cent, soluble phosphate, with from 30 to 

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



Superphosphates. — Phosphates dissolved with sulphuric acid. Their 

 composition varies accordmg to the richness of the phosphate from which 

 they are made, and the extent to which they have been dissolved. 



Higli-class Superphosphates are made from phosphates containing a high 

 percentage of phosphate of lime, and are very thoroughly dissolved. They 

 should contain between 30 and 40 per cent, soluble phosphaie, and very little 

 insoluble phosphate. 



Medium Superphosphates contain at least 23 per cent, soluble phosphate, 

 and all below that are 



Low-class Superphosphates made from minerals poor in phosphate of lime, 

 or insufficiently dissolved. 



Mineral Phosphates exist in great variety, and contain very various pro- 

 portions of phuspiiate of lime, viz., from 20 to 90 per cent. They are of use 

 as manures only when they are ground to the Hnest Hour. Even when ground 

 very tinely, some are so hard and insoluble iis to be of no use as manures. 



Compound Manures. — These are general manures containing nitrogenous 

 matter, phosphates, and potash, and their value depends not only on the 

 auiuunts of these constituents, but also on their fineness of division, :heir 

 solubility, and the sources from which their ingredients are derived. 



The general character of a few of the more common of these may be 

 indicated thus : — 



Tvjrnip Compounds. — These usually contain from 25 to 35 per cent, 

 phosphates, of which the half or more is soluble, and nitrogenous matter, 

 capuole of yielding from 2 to 4 per cent, of annnonia, and sometimes 1 or 2 

 per cent, of poUish. 



t*otato Compounds. — These are somewhat like the ])n'ceding, but contiiin 

 usually less pliosj>h;ile and a little more ammonia, from 3 to tl per cent.; 

 sometimes they contain no potash, but more fre([uently about 3 or 4 per 

 cent, is present, and in some instances twice as much. 



Bean Compounds. — These may contain from 10 to 20 per cent phosphates, 

 nitrogenous matter yielding from 3 to 7 per cent, of ammonia, and usually 

 a cousideral)le proportion of })oLash, often as much us from U) to 15 per cent. 



Cereal Compounds. — These usually contain al)out 20 per cent, phosphates, 

 mostly soluble, and nitrogenous matter, yielding from 3 to (5 per cent, 

 ammonia, and seldom conUiin potiish. 



Grass Compounds. — These are somewhat like the preceding, but may 

 conUiin less phosphates and more nitrogen, part of wliich may be in the 

 form of nitrate. 



