338 



The second, No. 2, is an orchard adjoining Concord river, 

 of a damp soil and of a very good quality. 



The third, No. 3, is a dry, sandy soil, considered by me of 

 no value, until I practised using saltpetre upon it as a dressing. 

 With regard to the mode or manner of using saltpetre upon 

 ground, I do not think it makes much difference, if it is but 

 put upon the ground. I have practised sowing it upon the 

 surface, and mixing and ploughing it in Avith, for aught I 

 know, equal results ; but I should be rather in favor of mixing 

 and ploughing it in. In this case it would require a larger 

 quantity, say 300 lbs. per acre ; the effects would be more slow 

 and lasting. In sowing upon the surface, it would require a 

 less quantity, say 150 lbs. ; but it would be necessary to repeat 

 the dressing yearly, until the crop should be satisfactorily large. 

 I am more in favor of bringing up the ground gradually, by the 

 yearly application of a small quantity of saltpetre, than I should 

 be by a larger quantity, and getting a large crop the first year." 



Since the foregoing, the same farmer has furnished me with 

 some additional information, which follows ; and again, the pres- 

 ent year, assures me of his continued success in this application. 

 I could have wished that the experiments had been made with 

 more exactness. 



" Since my communication to you in June last, respecting 

 the use of saltpetre as a manure, I have had a more particular 

 practical demonstration of its utility. 



Having an island in Boston harbor, called Spectacle island, 

 and its distance from land rendering it very expensive to fur- 

 nish manure for it, in the spring of 1838 I concluded to try the 

 experiment of using saltpetre as a substitute, and in order to 

 test its ability with some exactness, out of two acres which 

 had been cultivated the year before, half an acre was set apart 

 for the purpose of receiving 150 lbs. saltpetre, which were sowed 

 on the surface and the whole two acres were then ])loughed and 

 planted with potatoes. At harvesting, I found that there was 

 an increased crop upon the ground where the saltpetre had been 

 iapplied. I directed the man in charge to dry 5 hills upon the 



