558 PHOSPHATE AND SUPERPHOSPHATE OF LIME. 



produce an effect on land slowly but for a long time ; while the 

 effect of superphosphate, which act's immediately, soon dis- 

 appears. 



Superphosphate of lime is prepared by pouring over bones their own 

 weight of sxilphurio (or hydrochloric) acid, or half their weight; 

 or by using their acids diluted with twice their weight of water, and 

 when effervescence has ceased adding to the mass terrified sawdust, 

 peat charcoal, bpne-dust, or any other dry powder, which will reduce it 

 to a state fit for drilling. Or it is mixed with a large quantity of water, 

 and used in a liquid form. Or it may be prepared by placing 1} bushel 

 of finely-ground bones in a tub, with half their weight of acid, diluted 

 with four times the quantity of cold water ; after some hours, a few 

 bushels of fine mould and some coal-ashes should be added, so as to 

 make the whole amount to 15 bushels of compost. This may be used 

 in three days after its preparation, but would be better if kept longer. 

 The mixture is to be applied at the rate of little more than 2 bushels 

 per acre ; when it successfully rivals 16 bushels of bones. Another 

 way is the following. Take a large but shallow tub, about 18 inches 

 deep (regulating the size according to the quantity required), spread 

 the bones at the bottom of the tub, and add suflieient water barely to 

 cover them, then pour in the acid, stirring the whole mass with a, 

 strong fork ; an immediate effervescence takes place, and the bones 

 will be sufficiently dissolved for use in 48 hours, or even less. To 

 prepare the compost, mix half the quantity of peat or wood ashes — 

 according to quantity of bones used, passing it, if necessary, through a 

 coarse sieve — and afterwards adding as much dry mould as the drill 

 requires. This plan is better than, dissolving the bones in a heap of 

 dry mould, because, without great care, the acid, when poured on the 

 bones, is apt to escape into the mould, therefore it is better to add the 

 water first ; a tub is better than an iron vessel ; sulphuric acid having 

 a great affinity for metal wiU soon destroy it, but it has no effect 

 upon wood. 



If bones are to be used ^thout preparation it is best to buy half-inch 

 or inch bones, in order to avoid the frauds of dealers, who are apt to mix 

 plaster of Paris and other worthless materials with bone-dust. It has 

 also been suggested that it is advantageous to employ a preparation of 

 bone, which, being very flue, requires no digesting with sulphuric or 

 muriatic acid, and is both immediate and permanent in its effects : 

 that is to say, the sawdust of a button factory ; its effects are astonish- 

 ing. The progress of the plant after the first shower of rain is so great 

 that it has been employed by many gardeners with much advantage, 

 among other things upon Pine plants, and the effects were wonderful. 

 In 1842 Mr. Spencer, gardener at Bowood, used this bone-dust for 

 Pelargoniums, and with good results. The roots that were emitted into 



