BONES. 219 



attention of farmers in England, and the Highland 

 Agricultural Society of Scotland now publicly rec- 

 ommends this method as of all others the best for 

 finely pulverizing bones. Theoretical objections are 

 still urged against this mode of procedure, but its 

 superiority may be corroborated and justified in Scot- 

 land, as in Saxony, by the results of practical expe- 

 rience. 



4. Bone burnt to Whiteness^ Bone-blacky and Sugar- 

 Refuse. Wherever these substances can be procured 

 at moderate prices, they may indeed be employed as 

 valuable manuring agents ; but in using the two for- 

 mer it must always be kept in view that they no 

 longer contain gelatine and nitrogen^ and can accord- 

 ingly exercise a forcing action on the soil only when 

 conjoined with azotized manures (guano, rape-dust, 

 drainings, etc.). Their two principal constituents 

 are phosphoric acid and lime^ two substances, there- 

 fore, that are of great importance to plants in the for- 

 mation of their seed. They can, however, develop 

 their seed-forming power only when the plants to 

 which they are applied are supplied at the same time 

 with substances that form their strictly vegetable 

 parts, and more particularly with such as contain ni- 

 trogen or ammonia ; inasmuch as plants must vigor- 

 ously put forth stem, leaves, etc., before they can pro- 

 duce good and plentiful seeds. Individual instances 

 may, indeed, be found, which show that bones burnt 

 to whiteness and bone-black alone have brought forth 

 a very vigorous vegetable growth ; but it is more than 



