358 



TRANSACTIONS OF THE 



the porosity of that animal charcoal, capable of condensing the ambient 

 gas, and of yielding them gradually afterwards to the absorbent organs of 

 the vegetables. 



It is not known to be entirely the same with mineral phosphates ; endowed 

 •with a very strong cohesion, the mechanical means by which, even to this 

 day, we are only able to treat them, are insufficient to reduce them to a 

 state of division comparable to that of phosphate of bones. 



Besides, the importations of mineral phosphates from Estremadura into 

 Great Britain, have not produced amongst the agriculturist all the favora- 

 ble results where expected from them. One of us, M. Dumas, had the 

 opportunity, in 1850, of stating this fact, during a mission with which he 

 was charged by the Minister of Agriculture and Commerce, relative to the 

 agricultural improvements introduced into England, Scotland, and Ire- 

 land:* it does not appear that they have since succeeded in obtaining in 

 Grreat Britain as good effects from the mineral phosphates as from bones, 

 or the black residues of the refineries. 



All the above clearly admits, is the inferiority of the viincral phosphates, 

 while their after experiments more clearly show their entire worthlcssness. 



The worthy Secretary is in error, when he supposes that the difference 

 between mineral phosphate and bone phosphate is due to the incchanicaL 

 condition or porositij of the two : for if he had dissolved portions of each 

 in dilute muratic acid, so that each would have been in solution, and then 

 applied them respectively to the soil, he would have found that the dis- 

 solved phosphate from bones would fertilize plants and be readily assimi- 

 lated by them, while the dissolved mineral phosphate would have produced 

 no effect at all. We know that unless these mineral phosphate be first 

 made into erystallizable salts, and be then redissolved and crystalized a 

 great number of times, they cannot be made to answer any useful purpose 

 in agriculture for the use of the generation living at the time of their 

 pplication. This is just as true as that finely ground feldspar, although 



may contain 17 per cent, of potash, still it will not fertilize those plants 

 requiring potash. One pound of potash taken from the ashes of plants, is 

 worth more as a fertilizer, than tons of ground feldspar : and this is equally 

 true of every primary in nature. An analysis as now made, of either soils 

 or fertilizers, is an analysis of its powers for all time, and not of its avail- 

 able constituents for one, five, or ten years. 



The translation to which we have referred then goes on to say : 



On his part, M. Moride, who, with M Bohierre, has rendered indisput- 

 able services to agriculture, by analyzing the manures deposited in the 

 government dock-yards, and exposing certain frauds in commercial manures, 

 as proved, by direct experiment, the insolubility of many mineral phos- 

 tes in the weak acids, in the state in which they are now offered to ag- 



the Reports on Drainage, the Retting of Flax, the Peat Mosses, the Balicries, and 

 lercial Manures, published by the ]Minister, and the Memoirs of the Central Society 

 ure in 1850. 



