FERTILIZERS. 245 



of directing the attention of mineralogists and geologists to trap dykes, whose composition has 

 hitherto been disregarded ; or, it has been sufficient to class them under the general name of 

 trap dykes, or greenstone dykes. It is an easy matter to overlook and mistake the real cha- 

 racter of these intruded masses, inasmuch as they may all appear under a dingy green color, 

 and compact or slightly crystalline structure, as the Eupyrchroite and its associated rock at 

 Crown-Point seems to show. Phosphate of lime has received the trivial name of Apatite ; in 

 this mineral the elements are combined. 



Bones contain about fifty per cent of phosphate of lime, the remainder is gelatine. About 

 twelve per cent of carbonate of lime is also found in bone. Eupyrchroite contains nearly twice 

 the amount of phosphate of lime, according to Dr. Beck.* To supply phosphate of lime to the 

 soil bones have been principally employed. Bones owe their value both to the animal matter 

 (cartilage) and the phosphate of lime : of the two, however, the phosphate is by far the mo: t 

 important. We have seen already that this substance exists only in extremely minute quan- 

 tities in the soil ; and hence, in consequence of this fact, and another, that plants require it in 

 comparatively large quantities, it is exhausted at an early period after the lands are cropped 

 with grasses and grains. Bones which are buried in the earth gradually lose their gelatine, 

 while the mineral matter remains. 



The form in which bones are used with the greatest economy is in powder, or dissolved in 

 sulphuric acid. Circumstances will dictate the form which it is best to select. When bones are 

 immersed in sulphuric acid, the phosphate is partially decomposed, or the sulphuric acid displaces 

 a portion of the phosphoric acid, which is set free, or there is formed an acid phosphate of lime, 

 which is far more soluble than the bone earth before this change. In this condition it acts 

 promptly. When bones are buried in their entire state, they still produce good effects upon 

 vegetation ; but the effect is slow, and of course long continued. For some purposes, coarsely 

 pounded bones are highly useful : buried, for example, in a trench where it is designed to raise 

 grapes, a supply of the phosphate is obtained for years ; the bones, in the mean time, yielding 

 their organic and inorganic portions to the wants and necessities of the vine. By combustion, 

 the whole of the animal matter is consumed, and nothing remains but the earthy parts, which 

 still retain the form of the original bone. If they are acted upon by caustic lime or potash, the 

 animal matter, gelatine, is removed, though not entirely. In regard to the action of bones, 

 Liebig makes the following calculation : one hundred parts of dry bones contain from 32 to 

 33 per cent of dry gelatine ; now supposing this to contain the same quantity of nitrogen as 

 animal glue, viz. 5-28 per cent, then one hundred parts of bones must be considered equivalent 

 to two hundred and fifty parts of human urine. He remarks farther that bones remain un- 

 changed for thousands of years, in dry, or even in moist soils, provided rain water does not 

 have access to them. Bones of the glue makers, or those which have been employed for making 

 glue, when ground and mixed in a heap, become warm, and undergo a species of fermentation. 



* Chemistry as exemplifying the Wisdom and Benevolence of God. Appendix, pp. 136-139. 

 See Beck's Mineralogical Report, p. 240, giving phosphate of lime 92'0. 



