GUAXO AXD SULPHURIC ACID. 265 



moisten the guano -with Avater to which a little sulpliuric 

 acid has been added, and to mix it, after " twenty-four 

 liours, with saw-dust, turf-dust, or mould, instead of 

 gy})sum, and to strew this mixture over tlie surface of the 

 field. The rain water dissolves out the phosphate of 

 ammonia, which slowdy sinks into the ground, and all 

 parts of the soil with which the solution comes in contact 

 are enriched at the same time with phosphoric acid 

 and ammonia. If to the saw-dust, turf-dust, &c., gyj^sum 

 is added, it decomposes with the phosphate of ammonia 

 into very finely-divided phosphate of hme and sulphate 

 of ammonia, which are separated by the rain water ; the 

 soluble sulphate of ammonia penetrating deeper into the 

 groimd and carrj^ng down wdth it a small quantity of 

 the phosphate of hme, whilst the main bulk of the latter 

 is left on tlie top. 



On land poor in potash, the addition of w^ood ashes to 

 the guano, moistened with water and sulphuric acid, will 

 be found beneficial, as the carbonate of potash decom- 

 poses with the phosphate of ammonia into carbonate of 

 ammonia and phosphate of potash, and the potash does 

 not interfere with the phosphoric acid penetrating into 

 the soil. 



The results obtained, in the Saxon experiments, by 

 manuring with guano, afford a clear insight into all the 

 peculiarities observed in the action of this mamirinf 

 agent. 



If we compare the produce severally obtained by 

 manuring with guano and with farm-yard manure (see 

 page 100), we arc led to the following considerations on 

 the condition of the experimental field : — 



