NITRIC ACID. 29 



of mystery connected with the ways of nature 



in effecting a chemical combination between the 



two atmospheric constituents, as 



andcomp^unds. ^^^^ ^^ *^^ formation of ammonia. 

 Even scientific men cannot wholly 

 satisfy our thirst for more knowledge on this sub- 

 ject. The electric spark, passing through the at- 

 mosphere as lightning, is probably a most important 

 factor in the creation of nitric acid, and perhaps of 

 ammonia. Nitric acid is also produced in the soil 

 from nitrogenous substances by means of a low 

 form of organism. Scientists usually tell us of a 

 '^ vegetable ferment," and then leave the matter to 

 our imagination. 



It must appear evident that nitric acid cannot be 

 taken up by plants in this free and exceedingly 

 corrosive form. The acid nature urges to a combi- 

 nation with an alkali whenever an opportunity is 

 offering, and such is not lacking in nature. Nitric 

 acid may find potash, and combining with it, form 

 the harmless and well-known substance, saltpetre, 

 or nitre; or it may combine with soda, forming 

 nitrate of soda or Chili saltpetre (sometimes called 

 cubic saltpetre from the form of its crystals), or it 

 may combine with lime, forming nitrate of lime, or 

 with magnesia, forming nitrate of magnesia, etc. 



