NITROGEN IN NITRATES. 97 



plants. We understand (or have the means to learn 

 to understand) its true nature and habits, and have 

 no need of putting our reliance on uncertainties and 

 guess work — a most important advantage, not pos- 

 sessed by nitrogen in other forms, as in farm 

 manures, muck, and even in the commercial concen- 

 trated fertilizers. The chemist cannot always de- 

 termine how much of the nitrogen in such materials 

 is available, and how much is not. The most he 

 can do is to tell us the amount of ammonia in the 

 goods, but not whether any or all of it is in condi- 

 tion to feed plants or not. This is an element of 

 uncertainty which to me is terribly annoying. It 

 also affords protection to the manufacturer of poor, 

 but high-rated fertilizers, which are making a good 

 showing only in analysis, a protection which helps 

 him to palm off low-grade stuff on the farmer (who 

 buys it on strength of its high analysis published in 

 station reports) without fear of immediate detection. 



Whenever we wish to apply nitrogen to our crops 

 in the usual forms, we meet this difficulty, this ele- 

 ment of uncertainty. The use of nitrates, especially 

 nitrate of soda, alone can deliver us from this annoy- 

 ing and perplexing feature. It enables us to reckon 

 with definite figures. No sham or cheat about it. 

 We know what we have and apply it. For this 

 very reason its uses gives us so much satisfaction. 



Another nitrate form of nitrogen is saltpetre, and 



a very valuable one besides, of quick and often 



even more marked effects than the preceding, but 



too expensive for general purposes of 



m^^^^^TZs^, ^r«P f^^^i^g- Saltpetre, like nitrate 

 of soda, is imported from South 

 America, but nitrogen is not its only valuable con- 

 stituent; it has potash also, being a nitrate of 



