THE GROWTH AND NUTRITION OF PLANTS. 127 



And now in conclusion, let me urge upon you the importance of 

 trying this plan of feeding your crops. You cannot lose anything 

 by it, you may gain much. Test the matter and know of your 

 own knowledge whether j'our soil is like that on which we are 

 working in New Hampshire. 



The essay excited a deep interest, and held to the end the clese 

 attention of the large company present, and a vote of thanks to 

 Professor Whitcher, for his interesting and valuable paper, was 

 unanimously passed. 



Discussion. 



Joseph H. Woodford, spoke of the nitrate of soda as easily 

 converted into nitrate of potash, a useful fertilizer. He added 

 that any substance used as a fertilizer must be made soluble in 

 water, else it could not be available. 



Henry L. Clapp said that there are in different places in Can- 

 ada, large deposits of apatite, or phosphate of lime, containing 

 over forty per cent of phosphoric acid, and that apatite had 

 been mined for fifteen or twenty years, and carried to Eng- 

 land. He asked why it was not brought this way. It seems a 

 pity that the New Hampshire farmer, perhaps living near the 

 Canada line, should be obliged to procure his phosphate from 

 South Carolina, when a dozen phosphate beds are within one 

 hundred and twenty-five miles of Montreal, whence it is shipped 

 to England. In Nova Scotia large quantities of gypsum are 

 found, and very fine potatoes are raised there. Gypsum, under 

 the name of plaster, has been used in the culture of potatoes by 

 New England farmers, especially in the past. It is sulphate of 

 lime and contains forty-five per cent of sulphuric acid. Nova 

 Scotia soil seems to have enough gypsum in it by nature for the 

 successful culture of potatoes, while our soil seems to need it. 



Professor Whitcher said that he could only account for the 

 fact that Canadian apatite is not brought to this country, by the 

 protective duty laid on it. The only effect of sulphuric acid on 

 apatite or South Cai'olina phosphatic rock is to render them 

 soluble. He thought the fine quality of the Nova Scotia potatoes 

 could not be due to the gypsum, for just as good ones are raised 

 in the Aroostook region in Maine, where no plaster is used. In 

 New Hampshire not so much plaster is used as fifteen years ago ; 

 it is used as an absorbent in stables. 



