MANURES. 155 



ganic matter will all be driven off except the carbon, 

 \\-hich not being supplied with oxygen cannot escape. 

 In this form bones are called ivory black, or bone 

 'black; and they contain all of the earthy mutter 

 and carbon of the bones. The nitrogen having been 

 expelled, it can make no ammonia ; and thus far the 

 original value of bones is reduced by burning that 

 is, a ton of bones contains more fertilizing matter 

 before, than after, burning. This means of pulveriz- 

 ing bones is not to be recommended for the use of 

 farmers, who should not lose the ammonia forming a 

 part of bones, more than that of other manure. 



Composting bones with ashes is a good means of 

 securing their decomposition. They should be placed 

 in a water-tight vessel (such as a cask) ; first, three 

 or four inches of bones, then the same quantity of 

 strong unleached wood ashes, continuing these alter- 

 nate layers until the cask is full, and keeping them 

 always wet. If they become too dry they will throw 

 off an offensive odor, accompanied by the escape of 

 ammonia, and consequent loss of value. In about 

 one year, the whole mass of bones (except, perhaps, 

 those at the top) will be softened, so that they may 

 be easily crushed, and they are in a good condition 

 for application to the land. The ashes are. in them- 

 selves, valuable, and this compost is excellent for 

 many crops, particularly for Indian com. A little 

 dilute sulphuric acid, occasionally sprinkled on the 

 upper part of the matter in the cask, will prevent 

 the escape of the ammonia. 



Boiling bones under pressure, whereby their gela- 



