a 



of the laud which enabled the coal measures to be developed beneath 

 the surface of the sea, was doubtless compensated for by the elevation, 

 of the marine forests into a position favouring the deposits of nitrates.- 

 The wonderful conservative instincts of nature are thus demonstrated 

 in a most remarkable manner in restoring to the fields the nitrates- 

 leached therefrom in past ages. 



GENESIS OF GUANO. 



The fermentative action of germs in the production of nitrates on a 

 small scale and their storage to a limited extent are found going on in 

 many caves ut the present time. In these localities large numbers of 

 bats formerly congregated, and the nitrogenous constituents of their 

 dejecta and remains, collecting on the floors of caves practically devoid 

 of water, have undergone nitrification and become converted into nitric 

 acid. In a similar manner the deposits produced in rookeries, especially 

 in former ages, have been converted into nitric acid and preserved for 

 the use of the farmer. The well known habits of birds in congregating 

 in rookeries during the nights und at certain seasons of the year tend to 

 bring into into a common receptacle the nitrogenous matters which they 

 have gathered and which are deposited in their excrement and in the 

 decay of their bodies. The feathers of birds are particular) 7 rich in ni- 

 trogen, and the nitrogenous content of their flesh is also high. The 

 remains of birds, especially if it take place in a locality practically ex- 

 cluded from the leaching action of water, serves to accumulate vast de- 

 posits of nitrogenous matter, which is at once attacked by the nitrifying 

 ferments. If the conditions in such deposits are particularly favourable 

 to the process of nitrification, the whole of the nitrogen, or at least the 

 la ger part of it which has been collected in these debris, becomes finally 

 converted into nitric acid, and is found combined with appropriate bases 

 as deposits of nitrates. The nitrates of the guano deposits and of the 

 deposits of caves, as has already been indicated, arise in this way. If 

 these deposits be subject to moderate leaching, the nitrates may become 

 infiltered into the sorrounding soil. The bottoms and surrounding soil* 

 of caves are often found highly impregnated with nitrates. 



IMPREGNATION OF SOILS WITH NITRATES. 



When, on the other hand, these deposits take place in regions subjected 

 to heavy rains, the nitric acid which is formed is rapidly removed, to 

 be returned to the ocean and begin anew the circuit of life which will 

 finally restore it to the land. By reason of the accumulation of nitro- 

 genous matters in tropical regions, especially where there is a deficient 

 rainfall, it has been found that the soils of those regions contain a very 

 much larger percentage of nitrates than is found, for instance, in the 

 soils of the United States. Tuese nitrated soils are very abundant, 

 especially in Central and South America, where they cover large sur- 

 faces. In these soils the nitric acid, as a rule, is found in combination 

 with lime, while in the purer deposits of nitric acid it is almost con- 

 stantly found in combination with soda. In some South American soils 

 as much as 30 per cent, of nitrate of lime has been found. Not only 

 birds serve thus to secure deposits of nitrogen, but large quantities of 

 guano rich in nitrates have their origin in the debris of insects, frag- 

 ments of elytra, scales of the wings of butterflies, and other animal 

 matters which are often brought together in quantities of millions of 

 cubic metres. The products of nitrification in these deposits may also be 



