Chlorine, 

 Sulphuric acid, 

 Carbonic acid, 

 Potash and Soda, 

 Lime, 

 Magnesia, 

 Scsquioxide of iron, 



REVIEW AND CONCLUSION. 369 



Boussingault liua analyzed in this manner a soil from 



Calvario, near Tacunga, in Equador, South America, which 



possesses extraordinary fertility. 



He found its composition to be as follows: 



Nitrogen in organic combination, 0.343 



Nitric acid, 0.975 



Ammonia, O.OIQ.^- 



Phosphoric acid, "j 0.460 * 



0.395 



0.023 



traces 

 - Soluble in acids. ^ q„q 



1.256 

 0.875 

 2.450 



Sand, fragments of pumice, and clay insolul)le in acids, 83.195 

 Moisture, 3.150 



Organic miitters (less nit rogen), undetermined substances, 



and loss, 5.938 



100.000 

 This analysis is much more complete in reference to ni. 

 trogen and its compounds, than those by Baumhauer al' 

 ready given (p, 36:2), and therefore has a peculiar value. 

 As regards the other ingredients, we observe that phos- 

 phoric acid is present in about the same proportion ; lime, 

 alkalies, sulphuric acid, and chlorine, are less abundant, 

 while magnesia is more abundant than in tlie soils from 

 Zuider Zee. 



The method of analysis is a guarantee that the one per 

 cent of potash and soda does not exist in the insoluble 

 form of feldspar. Boussingault found fragments of pumice 

 by a microscopic examination. This rock is vesicsular feld- 

 spar, or lias at least a composition similar to feldspar, and 

 the same insolubility in acids. 



The inert nitrogen of the humus is discriminated from 

 that which in the state of nitric acid is doubtless all assim- 

 ilable, and that which, as ammonia, is probably so for the 

 most part. The comparative solubility of the two per 

 cent of lime and magnesia is also indicated by the analysis, 

 10* 



