272 Home Manvfacture of Portable Manures. 
quantity in the shortest time and at the smallest cost. It is enough 
to know that costly machinery is not required for home manu- 
facture, all that is requisite being simply a pit or two of the 
following dimensions and materials, with sufficient storage accom- 
modation. 
Having dug out a space large enough for a pit 10 feet long, 
6 feet wide, and 2^ feet deep, inside measurement, level the 
bottom and lay down 3 inches of mill-wrou(jht puddle, upon which 
place fire-brick flue-covers to form the sole of the pit ; build the 
sides and ends with common bricks (a brick and half thick), 
using no cement or plaster ; puddle outside and pack with fine 
sand. After the pit has been once used for dissolving, the in- 
terstices between the bricks will be filled up. A pit of this size 
is capable of holding two tons of ground bones. Pits may of 
course be made of smaller dimensions, if preferred. Strong 
wooden vats or tubs will suit equally well. In preparing super- 
phosphate, first throw into the pit the substance it is intended to 
dissolve ; pour over this one-fourth its weight of water, stirring 
and mixing well with a wooden rake or pole ; then add sulphuric 
acid, which may be twice the weight of the water or half the 
Aveight of the substance to dissolve : stir and mix the mass as 
before. Take, for example, 2 tons of bone-ash, containing 75 per 
cent, of phosphates, 10 cwt. or 112 gallons water, 1 ton sulphuric 
acid,* and allow to remain 48 hours in the pit : the above would 
yield 46 per cent, of phosphates, of which there would be 24 per 
cent, soluble, at an average cost of 5Z. 5^. to 5/. 10s. per ton. 
Superphosphate made by dissolving coprolites, apatite, or bone- 
ash, contains no ammonia, of which there is an appreciable 
quantity in superphosphate made from fresh (unboiled) bones, t 
Ammonia, when wanted, is generally supplied by the addition 
of sulphate of ammonia. 
Ground bones and coprolites require more acid to make the 
phosphates soluble than bone-ash. The finer bones are reduced 
the less acid will be required, and their division being more 
minute, more soluble phosphates will be obtained. 
When superphosphate of lime is removed from the pits, it is 
unnecessary to employ any drying substance to take up the re- 
dundant moisture ; for if allowed to remain in a heap for a 
sufficient time, the moisture will evaporate by the heat generated 
in the mass, and although losing in weight according to the time 
it remains in the heap (under cover), there will be an increase in 
* Brown sulphuric acid (called unconcentrated) 1"7 specific gravity, or of 140^- 
(by Twaddel's hydrometer), as being the cheapest, is best suited for the purpose 
of dissolving bones, the price ranging from 4Z. to 4Z. 15s. per ton. 
■f- From 4 to 4' 5 per cent, in unboiled bones, and from 2 to 3 in boiled bones. 
—P. H. F, 
