4 



CIRCULAR 436, U. S. DEPARTMENT OF AGRICULTURE 



metallic, or basic, elements present are usually about 26 percent of 

 sodium, 0.75 of potassium, 0.2 of calcium, and less than 0.1 percent of 

 iron and aluminum. The nonmetallic, or acidic, elements present are 

 customarily about 16 percent of nitrogen in the form of nitrates, 1 of 

 chlorine, mostly as chlorides but partly also as chlorates and perchlo- 

 rates, 0.1 of sulphur as sulphates, 0.02 of iodine, mostly as iodates, and 

 0.02 percent boron as borates. The total nitrate content, calculated 

 as sodium and potassium nitrates, varies from approximately 94 to 96 

 percent. In table 1 are given the analyses of four samples of Shanks- 

 process Chilean nitrate. 



Table 1. — Composition of Shanks-process Chilean nitrate 



Sample 

 no. 



Nitro- 

 gen 



Sodi- 

 um 



Potas- 

 sium 



Calci- 

 um 



Magne- 

 sium 



Chlo- 

 rine 



Iodine 



Sul- 

 phur 



Boron 



Mois- 

 ture 



Insol- 

 uble 



1 



Percent 

 15.92 

 15.98 

 16.03 

 16.06 



Percent 

 26.43 

 25.75 

 26.19 

 26.28 



Percent 



0.45 



1.10 



.36 



.54 



Percent 



0.21 



.24 



.21 



.01 



Percent 



0.04 



.07 



.04 



.06 



Percent 

 1.17 

 .55 

 .49 

 .36 



Percent 



0.017 



.011 



.032 



.019 



Percent 



0.08 



.12 



.06 



.04 



Percent 



0.017 



.01 



.058 



.03 



Percent 



0.36 



.40 



1.24 



1.26 



Percent 

 20 



2 



30 



3... 



20 



4 



.10 



Chilean nitrate produced by the Guggenheim process has a lower 

 moisture content than the product of the Shanks process. Probably 

 most of the moisture in the Guggenheim-process nitrate is absorbed 

 from the atmosphere subsequent to the manufacturing process. The 

 chlorine and potassium contents are also less, but the sodium content 

 is somewhat greater. The total nitrate content, calculated as sodium 

 and potassium nitrates, varies from about 98.3 to 98.8 percent. 

 Analyses of three samples of Guggenheim-process Chilean sodium 

 nitrate are given in table 2. 



Table 2. — Composition of Guggenheim-process Chilean nitrate 



Sample 

 no. 



Nitro- 

 gen 



Sodi- 

 um 



Potas- 

 sium 



Calci- 

 um 



Magne- 

 sium 



Chlo- 

 rine 



Iodine 



Sul- 

 phur 



Boron 



Mois- 

 ture 



Insol- 

 uble 



1 „ 



Percent 

 16.27 

 16.22 

 16.18 



Percent 

 26.79 

 26.60 

 25.61 



Percent 



0.16 



.16 



.13 



Percent 



0.07 



.07 



.21 



Percent 



0.04 



.06 



.04 



Percent 

 0.35 



Percent 

 0.009 



Percent 



0.08 



.05 



.10 



Percent 

 0.005 

 .012 

 .005 



Percent 



0.14 



.12 



.08 



Percent 

 0.10 



2 



.27 .09 



.23 



3 



.36 



.024 



.26 



Synthetic sodium nitrate of domestic origin is practically moisture- 

 free, the water content being less than 0.05 percent. The metallic 

 elements contained therein are approximately 26.8 percent of sodium 

 and less than 0.1 percent each of calcium and magnesium. The non- 

 metallic elements present are about 16.3 percent of nitrogen as 

 nitrate, 0.15 of chlorine as chloride, and 0.07 percent of sulphur as 

 sulphates. The insoluble matter is usually less than 0.1 percent. 

 The total nitrate content, present as sodium nitrate, is approximately 

 98.8 percent. 



The crystalline product of the old (Shanks) process sodium nitrate 

 may vary in color from pure white to yellowish, pinkish, gray, or even 

 violet tints. The products of the new (Guggenheim) process and of 

 the synthetic process are white. The old process product is somewhat 

 deliquescent, due to its impurities. As a result, it tends to absorb 

 water from the atmosphere and to cake. The Guggenheim process 



