308 



J. C. BRANNER — DECOMPOSITION OF ROCKS IX BRAZIL. 



Accepting the means here given as being as near the truth as we can 

 get with the available data, the amount of nitric acid brought down by- 

 rains in Brazil can be determined approximately from the rainfall. 



Taking the precipitation tabulated below and accepting the deter- 

 mination of nitric acid for Caracas as the one most likely to be the cor- 

 rect one for Brazil, we should have for the year the amounts given in 

 the second column of the table. 



Total Nitric Acid {HNO-i) free and in Ammonia in mean Rainfall in Brazil. 



Station. 



Rainfall (in 

 millime- 

 ters). 



Rio de Janeiro 974, 



Santos, S. Paulo 2,503. 



Alto da Serra 3,576. 



Sao Paulo \ 1,494. 



Alto Parnahyba 965. 



Uberaba 1 ,560. 



Morro, Velho 1,637. 



Gongo Soco 2,9.39. 



Itabira ■ 1,303. 



Queluz 1,453. 



Manaus, Amazonas 2,340. 



Pani 1,788. 



Ceara 1,491. 



Pernambuco 2,971, 



Victoria i 1,050, 



Colonia Isabel 1,037, 



S. JBento das Lages 2,179 



Bahia 2,394 



Nitric acid 

 .(HXO3) 

 (in millime- 

 ters). 



.00142 

 .00365 

 .00521 

 .00218 

 .00141 

 .00227 

 .00238 

 .00428 

 .00189 

 .00212 

 .00341 

 .00261 

 .00217 

 .00433 

 .00153 

 .00151 

 .00318 

 .00349 



Nitric acid 

 (HNO3) 

 from ammo- 

 nia in rain 



water 

 (in millime- 

 ters). 



Total 

 nitric acid 



(HNO,) 

 (in millime- 

 ters). 



.00444 

 .01141 

 .01630 

 .00681 

 .00440 

 .00711 

 .00746 

 .01339 

 .00594 

 .00662 

 .01067 

 .00815 

 .00679 

 .01354 

 .00478 

 .00472 

 .00993 

 .01091 



.00586 

 .01506 

 .02151 

 .00899 

 .00580 

 .00938 

 .00984 

 .01767 

 .00783 

 .00874 

 .'01408 

 .01076 

 .00896 

 .01787 

 .00631 

 .00623 

 .01311 

 .01440 



Determinations have been made at several places in the world of the 

 amount of ammonia brought to the earth in rain water. This ammonia 

 must also be counted among the indirect agencies of rock decomposition, 

 though it is ])erhaps no more important in Brazil than elsewhere, except- 

 in so far as the amount is greater, as shown by Muntz and Marcano, and 

 as the warm climate may increase its activity. Warington has shown 

 that all nitrogenous substances which yield ammonia are nitrifiable.* 

 Ammonia in contact Avith organic matter is soon converted into nitric 

 and nitrous acids. In water analyses, for instance, it is understood that 

 waters which give ammonia when fresh, 3d eld only nitric and nitrous 



* Jour. Chem. Soc, London, vol. xlv, p. G53. 



