No. 4. 



Manures. 



107 



continued application of guano, is attended 

 with bad results. In the vicinities of the 

 parts from which guano comes, near Peru, 

 there are places which become perfectly 

 sterile from its use; but some of these places 

 have been made fertile ai^ain by the applica- 

 tion of nitrate of soda; and at the present 

 moment there is an exchange going forward 

 of gu;ino tor nitrate of soda in the countries 

 which pr.iduce these substances. There are 

 certain places in South America where ni- 

 trate of soda is found, as we find an efHores- 

 cence on the walls of new buildings. Guano 

 is exported from one place, and nitrate of 

 soda from another, and we find the exchange 

 acting in the most beneficial manner. Where 

 guano has been acting, the application of ni- 

 trate of soda is found to supply some portion 

 of what is w'anted. Guano may be consi- 

 dered as a sort of representative of animal 

 manure. Again, greaves and rags, and all 

 such things, form an exceedingly good ma- 

 nure. These contain large quantities of ni- 

 trogen, and are capable, by their decomposi- 

 tion, of giving large quantities of ammonia. 

 They are exceedmgly good for those plants 

 which require these substances, such as 

 wheat and hops, upon both of which they 

 are known to produce the best effects. But 

 the application of these alone will bring 

 about a sterility of the soil, which is not de- 

 sired by the farmer, who wishes to gain year 

 by year, and not one year alone. Now, rags 

 and other things containing large quantities 

 of ammonia are very useful where mineral 

 ingredients have been supplied to a certain 

 extent. I have analyzed the mineral ingre- 

 dients of the rag ashes, and I found that they 

 contain 10 per cent, of mineral matter, and 

 in that 10 per cent, is a large quantity of 

 bone dust. The furnishing of ammonia to 

 the soil constitutes, perhaps, one of the prin- 

 cipal features of these manures. Now, as I 

 before intimated, we may reckon all the ani- 

 mal manures — such as shoddy, horns, hoofs, 

 trotters, rags, &-c. — as acting similarly to 

 gnano. The only difference is, that the 

 guano acts more quickly, because, the am- 

 monia is in a far more soluble state, and is 

 capable of being carried into the soil by the 

 first shower of rain. Now there are other 

 manures besides these; there is bone dust 

 or phosphate of lime. How is it that bone 

 du.«t has been found such a splendid manure? 

 Bones have been used in almost all quarters 

 with almost unqualified results; there are 

 very kw places in this empire where they 

 have not been found useful. I have heard 

 of their not having been very useful on the 

 Malm rocks — upper green sand; — I have 

 heard of two or three cases in which they 

 have been found of no service there; but, at 



all events, on general soils the bone dust has 

 been found of great use. It is easy to ac- 

 count for this. I have mentioned to you the 

 action of the rain, which is such that, sup- 

 posing one pint of water to dissolve a grain 

 per acre, 840 lbs. per acre are washed away 

 every year. But you will recollect that, in 

 addition to this, until very lately the plants 

 were taking bone dust constantly from the 

 ground, and thus providing the material for 

 the bones of animals, without any restitution 

 being made to the land. As tor man, all his 

 bones are, according to custom, deposited in 

 certain places, and never return to the land; 

 and until recetilly, the bones even of the 

 other animals were never restored to the soil. 

 The consequence was, that soils generally 

 became impoverished in bone dust. Bones 

 consist of certain kinds of animal matter 

 called "gelatme" and " fat," and of a por- 

 tion of mineral matter called " phosphate of 

 lime and magnesia." It is a very singular 

 thing that bones deprived of the animal mat- 

 ter act more quickly than the fresh bones. 

 The fact is, if you take some bones and 

 bruise them fine, and then take others and 

 burn them, the latter acts quicker than the 

 other. The fat of bones prevents atmosphe- 

 ric action on them ; and you know perfectly 

 well that unless they are soluble they are of 

 no use. They are of no avail to the farmer 

 if they are not soluble, and the more soluble 

 they are the better. The burnt bones are, 

 therefore, acted upon much more quickly 

 than the others, though we have a loss of 

 the animal matter. It is to Liebig that we 

 owe the suggestion of making bones much 

 more soluble than even burnt bones. The 

 main fact had been long known. The com- 

 mon method of making phosphoric acid form- 

 erly was to take a certain quantity of burnt 

 bones, and to mix them with a certain quan- 

 tity of oil of vitriol, by which means the 

 phosphoric acid of the bones was set at lib- 

 erty. The bones consist of phosphoric acid 

 and lime, with a little magnesia ; the sul- 

 phuric acid seizes upon the lime, and forms 

 sulphate of lime, or gypsum, and liberates 

 the phosphoric acid. Phosphoric acid is 

 quite soluble, as soluble as sugar. 



Now that is just the thing which the mind 

 of Liebig applied at once to land. " If," 

 said he, "we can just do the same thing for 

 the land, the first shower of rain will wash 

 this phosphoric acid down the land ; it will 

 there meet with lime, magnesia, and other 

 things, and form phosphate of lime and mag- 

 nesia, but in a state of the most minute di- 

 vision, so that it will be acted upon by the 

 smallest quantity of water. Now, without 

 any exception that I am aware of, where 

 bones and sulphuric acid have been tried, it 



