226 THE WASTE AND CONSERVATION OF PLANT FOOD. 



iiitiogeiious matters which cduic from the decay of the remaius of these 

 animals form true deposits of guauo, which are gradually spread arouud, 

 and which, in contact with the limestone and with access of air, suffer 

 complete uitrilication with the lixation of the nitric acid by the lime. 



Large quantities of thi^ guano are also due to the debris of insects, 

 fragments of elytra, scales of the wings of butterflies, etc., which are 

 brought together in those places by the millions of cubic meters. The 

 nitrification Avhich takes place in these deposits has been found to 

 extend its products to a distance of several kilometers through the soil. 

 In some places the quantity of the nitrate of lime is so great in the soils 

 that they are converted into a plastic paste by this deliquescent salt. 



It is suggested by the authors that the coexistence of the nitrate and 

 phosphate of lime is sufhcient in all cases to demonstrate the organic 

 origin of the nitric acid. It would not be possible to attribute such 

 an origin to the nitrate present in these soils if it could not be deter- 

 mined that it was thus associated with phosphate and other remaius, 

 the last witnesses of a former animal life. 



As a result of the observations of Miintz and Marcauo, they conclude 

 that it is not proper to accredit to the electrical discharges in the atmos- 

 phere the origin of the nitric acid forming these de})osits, although they 

 admit primarily the sourceof the nitric acid may have been due to elec- 

 tricity, but that it first was passed through the organism of the plant 

 and thence into that of the animal, whence it is accumulated in the 

 deposits referred to. 



The theory of Miintz and Marcauo in regard to the nitrates of soils, 

 esi)ecially in the neighborhood of caves, is probably a correct one, but 

 there are many objections to accepting it to explain the great deposits 

 of nitrate of soda which occur in many parts of Chile. Another point 

 which must be considered also is this: That the processes of nitrifica- 

 tion can not now be considered as going on with the same vigor as for- 

 merly. Some moisture is necessary to nitrification, as the nitrifying 

 ferment does not act in ])erfectly dry soil, and in many localities in 

 Chile where the nitrates are found it is too dry to sui)posc that any 

 active nitrification could now take place. 



The existence of these nitrate deposits has long been known.' The 

 old Indian laws originally prohibited the collection of the salt, but nev- 

 ertheless it was secretly collected and sold. Up to the year 1821 soda 

 saltpeter Avas not known in Europe except as a laboratory product. 

 About this time the naturalist Mariano de Eivero found on the Pacific 

 Coast, in the province of Tarapaca, immense new deposits of the salt. 

 Later the salt was found in equal abundance in the Territory of Anto- 

 fagasta and farther to the south iu the desert of Atacama, which forms 

 the Department of Taltal. 



'A most interesting article ou the subject may be found iu Jour. Roy. Agric. Soc, 

 1852, Vol. 13, page 349 et seq. 



