Superphosphate of Lime. 
149 
Phosphate of lime is a substance very diflficult of solution, and 
thus in a very dry season the effects of bones are often very 
slight and imperfect. Superphosphate of lime, on the other 
hand, is extremely soluble, so much so that the vitriolized bones 
can be entirely dissolvetl or suspended in water, and thus applied. 
This at once explains the cause of the valuable properties of the 
preparation. The bones in their natural state are extremely 
indigestible, the acid cooks them — converts them into a species 
of soup which can readily be eaten and digested by the young 
turnips. The adamantine fetters with which the various elements 
composing 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 affinities. The chemical changes which take place 
between the sulphuric acid and the organic portion of the bones 
are no doubt very complicated. Sugar is one result, and probably 
sulphate of ammonia is another; but I cannot venture to state 
what quantity of sulphuric acid may be necessary to effect these 
changes. If we presume that one-third is the proportion of sul- 
phuric acid employed, then there will remain 17 lbs. 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 
phosphorus 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 sulphuric acid. 
Thus if we suppose 180 lbs. to be the quantity employed, by 
burning it will be reduced to 120 lbs., requiring 60 lbs. of acid 
to form superphosphate, which would be one-third the weiarht 
of the bones previous to burning. I suppose, however, that in 
this case an excess of acid is required to render the process com- 
plete, 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 probably the precise quantity most de- 
sirable will be 42 per cent, of acid. I may, however, observe 
that in an experiment during the last season, in which one por- 
tion of the land was manured with bones and acid in different 
proportions, that which had more bones and less acid proved to 
be a 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 by weight of water is mixed with four of acid 
