No. 151.] 373 



phate of lime, selenite, or gypsum is an abundant natural product, 

 and may be formed artificially, by adding sulphuric acid to the solu- 

 tions of the salts of lime. 



Farmers should be very particular in the selection of their lime 

 for agricultural purposes. I speak from experience in this matter; 

 having sown within the last seven years, more than 10,000 bushels, 

 3,000 of which were stone lime, and the balance oyster shell. The 

 stone lime was obtained on the banks of the Hudson, and contained, 

 as most limes do, a large per centage of magnesia. By its use, I 

 am convinced my land was injured, and it may require several years 

 to recover from the bad effects produced; the fact is, all lands re- 

 quire magnesia in minute quantities to grow the usually cultivated 

 grains; and all lands contain a sufficient quantity for agricultural 

 purposes, therefore, by adding lime containing a large per centage 

 of this substance you add a mineral not required, and consequently, 

 take up the space that should be occupied by some more useful in- 

 gredient. I would not condemn 'all the stone lime found on the 

 banks of the Hudson, as I have examined but few of them; those 

 few however, have all been strongly impregnated with magnesia. 

 Statuary marble is the only perfectly pure carbonate of lime, or 

 rather if not perfectly pure, more nearly so than any other stone 

 lime. In examining lime stones, place them in strong acid, and if 

 they do not effervesce very rapidly, and yet are so hard as to enable 

 you to mark glass with small pointed pieces, you may be assured 

 they contain flint earth, and possibly clay. If the lime is not suffi- 

 ciently hard to scratch glass, and on effervescing w^th acids the ac- 

 tion is very slow, and the solution resembles cream, you may make 

 up your mind that it contains magnesia. When the lime stone ap- 

 pears brown or yellowish red, it contains iron. 



The chemical effect of burning stone lime is, that the water and 

 carbonic acid gas are driven off, which amounts to about 35 per 

 cent. After having been exposed to the atmosphere on your farms for 

 a certain length of time, the carbonic acid of the air is again absorb- 

 ed by the lime, which reduces it to the state of chalk, or carbonate: 

 if taken up by plants before it becomes a carbonate, the charcoal 

 and oxygen abounding in all plants, immediately converts it into 

 one. Caustic lime applied to your soil, reduces hard vegetable mat- 

 ter into a state easy of decomposition. When the lime takes the 

 chalk form, it furnishes matter requisite to supply the inorganic 

 structure to plants which grow in its vicinitj. You may always 

 lime land advantageously which abounds in hard, dry, undecomposed' 



