174 



CHEMICAL MANURES.i 



On cooling, the solution of ossein previously concentrated by evapora- 

 tion assumes a gelatinous consistency, and on drying it is converted 

 into solid tablets which are marketed as glue. The ratio between 

 the organic substance and the mineral matter in bones continually 

 varies, not only with the origin and race of the animal from which 

 they come, but also in one and the same individual, according to 

 whether the bones are hard or spongy. In spongy bones the or- 

 ganic matter is higher by 4-5 per cent than in hard bones; the 

 amount of carbonate of lime is likewise higher by 11 per cent, 

 whilst the percentage of phosphate of lime is less by 15-5 per cent. 

 It is evident that the percentage of nitrogen and phosphoric acid 

 in bones is very variable! Their fat content calculated on the 

 dry substance is from 10 to 12 per cent. Berzelius has given the 

 following analysis of an ox bone freed from periosteum : — 



TABLE XLIX.— ANALYSIS OF AX OX BOXE. (BERZELIUS.) 



Cartilage completely soluble in water ) 

 Vessels „ „ „ „ J 



Tribasic phosphate of lime and a little CaFo 

 Carbonate of lime . . . . . 



Phosphate of magnesia . . , . 



.Soda with very slight trace of XaCl 



Per cent. 



33-30 



58 •35 

 3-87 

 2-05 

 2-45 



100-00 



This theoretical composition of bone built up from a select bone 

 does not represent the average composition of the bones used by 

 glue manufacturers, because the bones have undergone various 

 treatments, such as boiling, fermentation, which may have altered 

 their nature. Besides, bones are supplied by different animals. 

 Practically ordinary bones received in factories respond in round 

 figures to the following analysis : — ^ 



TABLE XLIX. (a).— ROSINATE ANALYSIS OF BONES AS SUPPLIED 



TO MANURE FACTORIES. 



Per cent. 

 Moisture ........ 12 



Organic matter ..... 

 Tribasic phosphate of lime and magnesia 



X ciX ••••••• 



Carbonate of lime, sand, etc. 



28 



44 



10 



5 



99 



Commercial bones always contain more or less moisture, 

 butchers' bones up to 30 per cent, and they are mixed with other 



1 This looks very much like an average analysis of ordinary " rag ' bones. 

 Ordinary London '-rag" bones yield 11 per cent of fat when extracted by 

 petroleum spirit. — Tr. 



