AGRICULTURAL CHEMISTRY AND GEOLOGY. 151 



silica can never enter the rootlet of a plant, however fine the powder, unless it is in solu- 

 tion ; and that the finest powder of sand or silica differs as much in solubility from nascent 

 silica as sand differs from sugar. The importance, then, of soluble silica to grasses and 

 wheat, and especially in corn, and, indeed, its value as manure, has long been recognised. 

 (See Liebig's Chemistry, American edition, 1841, p. 200.) It was first supposed that potash 

 was the vehicle for its conveyance to every part of the plants ; but the modern idea is, that 

 ammonia is the main instrument of its conveyance. Certain it is, that it loses its base at the 

 instant of its deposition on the stem ; and if potash were the base, then it would be neces- 

 sary that the potash be carried back again to the earth, and the plant would be constantly 

 embarrassed by excrementitious matter ; whereas, the ammonia being volatile, evaporates, 

 and leaves the glassy coating, or element of strength, on the surface of the stem. Thus, it 

 is found that more ammonia is actually exhaled from plants than we ever give them in the 

 form of manure ; and it is strongly suspected that soluble silica is really the manure, while 

 ammonia is merely the vehicle for the conveyance of soluble silica through the plant. When 

 the carcass of an animal falls in the field, the luxuriant grass or grain " falls," on account 

 of the absence of the relative amount of soluble silica, or the excess of ammonia uses up at 

 once all of this necessary element that is available. 



Two years since, I manured two lands in the centre of my oatfield, the one with Peru- 

 vian guano, the other with soluble silica, leaving a land unmanured between. The propor- 

 tion of straw on the guanoed land was very much increased ; but last summer the same field 

 was in wheat, and a corresponding diminution in the proportion of straw was noticed on the 

 land that had been guanoed two years since ; and what is more remarkable, the land on 

 each side of the guanoed land averaged seven hundred and forty-six pounds more of wheat- 

 straw per acre, although no manure of any kind had been applied to either since it was in 

 oats ; whereas the silicated land not only produced more straw than either of its unmanured 

 neighbors, but also excelled the guanoed land in wheat nearly throe bushels per acre, and 

 ripened earlier than any oth'er part of the field. 



The difference between the silicated land and the unmanured averaged nineteen hundred 

 and sixty-six pounds, while it also produced nine and one-tenth bushels of wheat more than 

 the adjoining unmanured lands. A part of my oatfield of last summer exhibited the same 

 increase in the weight of the straw, although no silicates have been applied since it was in 

 corn two years since. But the most remarkable result was obtained in my cornfield of this 

 year, where the corn on the silicated portion averaged ninety-three pounds per shock, while 

 one part unmanured only weighed forty-two pounds per shock ; each shock represented 

 sixty-four hills of corn, and the average of thirty-one shocks was taken. This manure was 

 applied in my presence, and I personally gathered and weighed the produce of each separate 

 shock in the field with my own hands ; therefore I can vouch for the correctness of the re- 

 sults. And now, can we not account for the well-known and remarkable efficacy of dissolved 

 bones on this principle, when compared with normal phosphate of lime, whether it be in the 

 form of bone-ash, ground bones, or phosphate guano ? 



"Bones have been used with profit at the rate of from $20 to $60 per acre ;" and it has 

 been repeatedly demonstrated that one bushel of dissolved bones, for immediate effect, is 

 equal to five times as much ground bones ; in other words, that one pound of nascent or 

 soluble phosphate of lime is worth more than five pounds of normal or natural phosphate of 

 lime, or bone-earth. It will be admitted that every acre of land on the face of the earth 

 contains from one-tenth of 1, to 4 per cent, of lime and magnesia; and if only one-tenth of 

 1 per cent, at the depth of cultivation, even then each acre must contain from fifteen hun- 

 dred to two thousand pounds of lime and magnesia. Now, it is manifest if ten or even thirty 

 bushels of dissolved bones were applied to an acre, the first rain would convert all of the 

 free phosphoric acid or biphosphates that they contain into neutral nascent subphosphates ; 

 and it is therefore nascent subphosphate of lime that is taken up and assimilated by the 

 plant. Thus we are enabled to account for the wonderful effects of what are called in com- 

 merce biphosphates, which really contain very little free phosphoric acid, but all of the 

 phosphoric acid exists as neutral nascent phosphate of lime. The fact is, that dissolved 

 bones are unmanageable as a manure in this country, (in England biphosphates are applied 



