EEPOliT ON NITRIFICATION. 



PEESENTED TO THE SMITHSONIAN INSTITUTION IN 1858. 



BY DR. B. F. CRAIG. 



I have the honor to acknowledge the receipt of a communication 

 from the Smithsonian Institution, requesting me to furnish information 

 and suggestions upon the subject of the formation of nitre, with espe- 

 cial reference to its production in this country, and in accordance 

 with this request I respectfully submit the following. 



An opinion upon any one branch of the subject of nitrification can- 

 not be fairly based upon anything but a statement of our knowledge 

 of the whole, nor can the practical value of any source of nitre be 

 estimated without a comparison of it with other known or attainable 

 means of supply. In order, then, t« be enabled to give the required 

 information, I have felt myself called upon to take up the whole sub- 

 ject of nitrification, a subject of much difficulty and intricacy, the 

 obstacles to the study of which are increased by the circumstance 

 that information on it is only to be found scattered here and there 

 through the pages of scientific publications. The difficulties attend- 

 ing it, together with the pressure upon me of other occupations, I 

 would offer as an apology for my delay in answering your communi- 

 cation. To obtain clear ideas on those points on which information 

 is most to be desired, it will be necessary to consider the subject 

 under the following heads : 



1st. Our knowledge of the la^^'s which govern the formation of nitre. 



2d. The manner and extent of its production in nature.* 



3d. The methods that have been practiced for its artificial formation. 



4th. The methods of artificial formation that have been suggested, 

 or those which the present state of our knowledge would suggest. 



5th. The experimental investigations that it would be desirable to 

 make, lor the proper advancement of the theory and practice of the 

 manufacture of nitre. 



I. Since nitrates t are continually being produced under different cir- 



■"• Nitre is not found accumulated ia masses like most minerals, but forms continuously 

 in various places, whence it is extracted from time to time. 



f The nitrates that are to be met with where nitrification has taken place, and which, for 

 the sake of convenience, may be spoken of as a class, include saltpetre or the nitrate of 

 ootash, the nitrate of soda, the nitrate of lime, and the nitrate of magnesia. Their chem- 

 ical formulas are as follows : 



Nitrate of potash, NOg K. 



Nitrate of soda, NOg Na. 



Nitrate of lime, NOg Ca. 



Nitrate of magnesia, NOg Mg. 



The three last are convertible by simple means into nitrate of potash, the conversion 

 requiring, of course, a supply of potash, which is usually obtained in the form of a ley of 

 wood ashes. 



The nitrate of soda is met with in South America Those occurring elsewhere are, mainly, 

 the nitrate of lime and the nitrate of potash. 



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