170 ON THE USE OF 



tlieir natural state are extremel}^ indig-estible, tlie acid cooks 

 them — converts them into a species of soup, which can 

 readily be eaten and dig-ested by the young- turnips. The 

 adamantine fetters with which the various elements com- 

 posing bones are bound so compactly together are, by means 

 of this new agent, burst asunder — the compact is broken, 

 and each constituent element is left to pursue its own course, 

 and to exercise its own natural af&nities. The chemical 

 changes which take place between the sulphuric acid and 

 the organic portion of the bones are no doubt very com- 

 plicated. Sugar is one result, and probably sulphate of 

 ammonia is another ; but I cannot venture to state what 

 quantity of sulphui'ic acid may be necessary to effect these 

 changes. If we presume that one -third is the propor- 

 tion of sulphuric acid employed, then there will remain 

 17 lb. to act on the organic portion of the 4 bushels of 

 bones, the remainder having- been required by the earthy 

 portion. 



We find that manufacturing- chemists, in the preparation 

 of ]ihosphorus from bones (now largely required for lucifer 

 matches), first destroy the organic part of the bones by means 

 of fire, and then mix the remainder with half its weight of sul- 

 phuric acid. Thus, if we suppose 180 lb. to be the quantity 

 em]doyed, by burning it will be i*educed to 120 lb., requiring 

 60 lb. of acid to form superphosphate, which would be one- 

 third the weight of the bones previous to burning-. I sup- 

 pose, however, that in this case an excess of acid is required 

 to render the process complete, as one-half would otherwise 

 appear to be more than the quantity demanded. 



From these and other reasons, we may justly consider that 

 the proportion of acid to the bones should never be less than 

 one-third, nor more than one-half. The former, I think, is 

 the most economical, but probablv the precise quantity most 

 desirable will be 42 per cent, of acid. I may, however, 

 observe, that in an experiment during- the last season, in 

 which one portion of the land was manured with bones and 

 acid in different proportions, that which had more bones and 

 less acid proved to be somewhat better crop than where fewer 

 bones and more acid were used ; the expense being the same 

 in both instances. 



3. The proportion of water to be mixed with the acid will 

 next receive our attention. 



When one part b}^ weight of water is mixed with four of 

 acid, the temperature is raised to 300° Fahrenheit. It is, 



