216 MAPLE 



nature of the soil, and the peculiar mode of treatment which the land has received 

 on the part of the farmer. 



However, nearly all special artificial manures, generally speaking, may be arranged 

 under two heads. They are either: 1. Nitrogenised Manures, or, 2. Phosphatic 

 Manures. The first may be used with almost equal advantage for wheat, barley, oats, 

 for rye, and on good land likewise for grass. The second are cniefly used for root-crops. 



Nitrogenised artificial manures frequently are nothing more than guano, diluted with 

 gypsum, salt, peat-mould, earth, &c. In fact, guano is the cheapest ammoniacal 

 manure; for which reason it is so largely employed for compounding low-priced 

 wheat-manures, grass-manures, &c. &c. 



Good manures for cereals may be made by blending together fine bone-dust, or 

 bone-dust dissolved in sulphuric acid, sulphate of ammonia, salt, and gypsum. 

 These manures will be the better the more sulphate of ammonia they contain. In 

 1873 we imported 70,055 tons of bones of animals and fish for this purpose. 



Turnip-manures, and artificial manures for root-crops in general, consist prin- 

 cipally of dissolved bones, or dissolved coprolites and other mineral phosphates. 

 They are, in fact, superphosphates of various degrees of concentration. The more 

 soluble phosphate a root-manure contains, the better is it adapted to the purpose for 

 which it is used. 



Most samples of superphosphate contain little or no ammonia, or nitrogenised 

 organic matters. 



Blood-manure is a superphosphate, in the preparation of which some blood is used. 



In preparing superphosphate from bones, it is essential that they should be reduced 

 to fine dust. This is moistened with about ^ its weight o.f water, after which another 

 third to one half of brown sulphuric acid is added. The pasty mass is allowed to 

 cool, in the muring vessel, or when large quantities are prepared, the semi-liquid 

 mass in the mixer is run out still hot, fresh quantities of bone-dust, water, and acid 

 are put in the mixer, and after 5 or 10 minutes the contents allowed to run out. and a 

 fresh quantity prepared as before. The successive mixings are all kept together in one 

 heap for 1 or 2 months ; the heap is then turned over, and if necessary, the partially- 

 dissolved bones are passed through a riddle. 



In a similar manner, coprolites, bone-ash, apatite and other phosphatic minerals are 

 treated with acid. It ought to be observed, however, that the quantity of brown sul- 

 phuric acid necessary for dissolving coprolites must be at least ^ths of the weight of 

 coprolite powder, for coprolites contain much carbonate of lime, which neutralises sul- 

 phuric acid. Even 75 per cent, of brown acid are not always sufficient to dissolve com- 

 pletely coprolite powder, and as the proportion of carbonate of lime in coprolites and 

 phosphatic minerals varies considerably, it cannot be stated definitely what amount of 

 oil of vitriol should be used in every case. The safest plan, therefore, for the manu- 

 facturer is, to ascertain from time to time whether the proportion of acid which he 

 has used has converted nearly the whole of the insoluble phosphates in coprolites into 

 soluble phosphates, and if necessary to add more acid. In the case of bone-dust, it 

 does not matter if the whole of the bone-earth is not rendered soluble ; bones even par- 

 tially acted upon by oil of vitriol, become sufficiently soluble in the soil to prove effi- 

 cacious for the turnip crop. But the case is different, if mineral phosphates, such as 

 apatite or coprolite powder, are employed in the manufacture of superphosphate. In- 

 soluble phosphates in the shape of coprolite powder are not worth anything in an arti- 

 ficial manure, for they are too insoluble to be taken up by the turnip crop. It is 

 therefore essential to employ a quantity of acid, which is amply sufficient to convert 

 the whole of the insoluble phosphate of lime in coprolites into soluble, or biphosphate 

 of lime. A. V. See APATITE ; COPROLITES ; PHOSPHATES. 



We exported, in 1873, artificial manures to the value of 671,550. 



IVXAPIiX:, or Plane. (Erable, Fr. ; Ahorn, Ger.) Acer campestre, the English 

 or field maple. The wood of this tree is compact and finely veined; it is used in 

 France and other parts of the Continent for furniture, and it makes excellent charcoal. 



Acer platanoides. The Norway maple. This wood is soft, but being finely grained 

 is capable of receiving a good polish, and looks well. 



Acer pseudo-platanus. Sycamore, groat maple, or false plane. The wood is of a 

 compact grain, and does not warp or become worm-eaten. 



Acer saccharum. Sugar maple. This tree is extensively cultivated in America 

 for the sugar which is extracted from it. The wood is frequently used for furniture, 

 having a silky lustre when polished. 



Acer striatum. Striped barked maple. This tree is grown in America, and as 

 the wood is finely grained and white, it is much used as a substitute for holly by 

 furniture-makers. 



The Russian maple is thought to be the wood of a birch-tree. It differs in many 

 respects from the American maple, but is sometimes used as a substitute for it. 



