NITRATE OF SODA. 143 



and Crispo* gives the following analyses of specimens of Chili 

 saltpetre from the same cargoes as those which had been 

 observed to have a harmful effect upon plants : 



I. II. III. IV. 



Nitrogen ... 15-44 15-70 15-40 15-40 



Water ... ... 1-97 1-69 3-05 3'32 



Sodium nitrite ... 0-00054 0-00054 0-00054 0-00054 



Sodium chloride ... 0-15 0-17 1-55 1-09 



Magnesia ... 0-089 0-077 0-217 0-25 



Sodium iodate ... 0-004 0-015 0-040 0-033 



Sodium perchlorate 1-04 0'97 0-93 0-90 



That sodium perchlorate has an injurious effect on most 

 plants appears certain, but the quantity which is permissible 

 in sodium nitrate is a matter on which much diversity of 

 opinion appears to exist. 



Zaharia (just quoted) found that solutions containing less 

 than 0*1% of perchlorate had little or no effect upon the ger- 

 mination of beet, rye, and wheat, though oats were affected. 

 The seedlings, however, were injured by even much weaker 

 solutions, oats being most affected, then rye, wheat, and lastly 

 barley ; a O'OOl % solution had no effect on barley and wheat, 

 but injured oats. He found that the application of nitrate 

 containing 1% perchlorate decreased the production of grain 

 and straw about 4 %, while nitrate containing 2 % lessened the 

 grain by 25 % and affected the straw to an even greater extent. 



De Caluwef found that sodium perchlorate was more poi- 

 sonous than the potassium salt, rye and maize being the most 

 susceptible crops. The application of 150 grammes of sodium 

 nitrate to the square metre gave a crop of 6- 7 kilogrammes 

 with pure nitrate, but when the nitrate contained 2*67% 

 of sodium perchlorate the yield was only 3 -35 kilogrammes, 

 while nitrate containing 4 to 5% of the perchlorate proved 

 fatal in all cases. 



Sodium nitrate is the most important artificial source of 

 nitrogen and has taken the place, to a great extent, of guano ; 

 as the supplies of the latter substance have now been almost 



* Annales Agronomiques 1898, 92. 

 t Bull. Assoc. Beige ties Chim. 12, 363 ; Jour. Soc. Chem. Ind. 1899, 1141. 



