46 



ket are intended to supply both phosphoric acid and ammonia, 

 but their chief value is for a supply of the latter. If applied 

 alone to the soil, it benefits those crops which require larger 

 amounts of ammonia; but as the bones of the fish are not com- 

 minuted or finely ground, the phosphoric acid contained therein 

 is of scarcely any use to growing plants, and the amount re- 

 quired for the crop must be drawn from the store house of the 

 soil. 



This has been sought to be remedied by treatment with sul- 

 phuric acid previous to manipulation, but as the bones exist as 

 bones, and not as powder, the solvent power of the acid is mate- 

 rially diminished. 



The best grade of this material is what is known as fish 

 scrap, as fish guano proper is nearly all water. 



Planters are often of the opinion that a bad smell arising 

 from a fertilizer is a test of its manurial value, and especially 

 that it indicates the presence of ammonia. This is entirely a 

 mistake; the smell of ammonia is that of hartshorn, and in any 

 fertilizer in which the ammonia exists as free carbonate of 

 ammonia, this smell will be observed, as in Guanape guano. Ifj 

 however, the ammonia, is combined with a strong acid, no smell 

 of hartshorn will be perceived as in the true Chincha or Peru- 

 vian guano, or in sulphate of ammonia. 



The cause of the bad smell is not exactly ascertained, but 

 seems to be due to the presence of the gases, sulphuretted and 

 phosphoretted hydrogen, which gases are combinations of sul- 

 phur and phosphorus with hydrogen. The sulphuretted hydro- 

 gen is familiar as the odor ofr rotten eggs. 



Sulphate Ammonia is also a very concentrated supply of this 

 material for crops. It is chiefly made from the refuse of gas 

 works of large cities. Coal, from which gas is made, was origi- 

 nally organic matter trees, plants. These contained nitrogen, 

 and when subjected to heat, in a closed retort, the nitrogen 

 combines with the hydrogen to form ammonia. This, together 

 with all the tarry matters of the coal distils over, and is con- 

 densed in the "hydraulic mnin," which is a necessary process 

 in gas making. The liquor containing most of the ammoniacal 

 salts is then drained off, treated with sulphuric acid, and evapo- 

 rated until the sulphate of ammonia crystalizes. It is allowed 

 to cool, and is drained. The supply of this, however, is limited, 

 and its chief use is for the cereal crops, to which it is better 

 adapted than to cotton. 



Nitrate of Soda. Ammonia has generally been considered 

 the form in which nitrogen is assimilated by crops, but nitrogen 

 in the form of nitric acid, or any of the compounds of oxygen 

 and nitrogen, gives excellent results, so that nitrate of soda 

 forms one of the most regular and best supplies tor nitrogen 

 for plants. This material is entirely obtained from the rainless 

 desert of Atacama, in Peru. It there exists in vast beds, and 



