I. AGRICULTUKE AND RURAL ECONOMY. 425 



remains to investigate the progress of the change in a stack 

 of hay which produces the necessary elevation of tempera- 

 ture for carbonization. The normal temperature and exter- 

 nal appearance indicate that, owing to the poor conducting 

 power of hay, all the heat evolved by chemical clianges in 

 the interior is accumulated there. May not mineral coal 

 have been formed by a process somewhat similar ? As prac- 

 tical precautions against conflagrations from this cause, care- 

 ful drying is recommended, and also that stacks be not too 

 large nor confined; and, finally, that intermediate layers of 

 straw or of boards or poles be introduced in such a way as 

 to facilitate ventilation. 33 (7, 1873, CLXVIL, and 28 C, 

 May, 1873, 318. _____ 



COXVERSIOX OF BOXES IXTO FERTILIZERS. 



The following simple method, originating in Russia, has 

 been found excellent in practice, as all the valuable ingre- 

 dients of the material employed appear to be converted into 

 soluble compounds, readily taken up by the plant. Unpul- 

 verized bones and wood-ashes are filled in a trench, thrown 

 up three to four feet deep, in alternate layers, about half a 

 foot thick, the bottom and top layers being ashes, and each 

 layer being saturated with .water. Stakes are driven into 

 the pile, to the bottom, three feet apart, by removal of which, 

 every eight or ten days, as much water is poured in through 

 the holes as may be necessary to keej) up the saturation of 

 the ashes in the fermenting mass. After eight weeks, the 

 ashes, and the bones, already softened, are mixed, by forking 

 up the whole pile, and left to further decomposition, the nec- 

 essary water being supplied from time to time as before. 

 After three months, the mass having been stirred over thor- 

 oughly two or three times during the interval, the decompo- 

 sition of the bones is so complete that only pieces of the 

 larger ones are left, which are removed to another pile. For 

 want of wood-ashes, horse manure may be used, in square 

 trenches, the bones being soaked several days previously in 

 water. The layers of bone should be three inches deep, and 

 of manure twelve inches, and the w^ater in which the bones 

 were soaked is to be employed with other water to satu- 

 rate the layers. The pile should finally be covered with a 

 heavy layer of earth. In ten months the decomposition 



