Soluble and Insoluble Phosphates. 
155 
insoluble form within the soil itself. Insoluble phosphates in a 
precipitated condition are not only greatly more bulky than in 
the form of the finest powder which can be obtained by me- 
chanical means, but are also more soluble in water than merely 
powdered phosphate of lime. In consequence of this voluminous 
and extremely fine state of division in which phosphate of lime 
is precipitated in the soil, the application of a few hundredweight 
of superphosphate per acre in most cases answers better and is 
more economical than two or three tons of a phosphatic marl, 
or half a ton of coprolite powder. Nevertheless there are, no 
doubt, soils upon which marl may be applied with greater 
advantage than superphosphate, and there are others upon which 
fine bone-dust, or bone-dust treated with a little acid and only 
partly rendered soluble, is a more suitable manure for roots than 
dissolved bones rich in soluble phosphate. The question under 
discussion, however, is not what is the best manure for root- 
crops on various kinds of soils, but is it good or bad economy 
to treat phosphatic materials with acid ? or, in other words, to 
manufacture them into superphosphate or to apply them in a 
raw state to the land. 
It can scarcely be imagined that all the many farmers who 
have applied, year after year for more than twenty years, dis- 
solved bones or superphosphate as a manure for turnips and other 
root-crops can have been mistaken in considering it true economy 
to use these manures in preference to undissolved bones. 
The earliest notice of the great discovery, as the late Mr. Pusey 
called the treatment of bones with acid, and the use of dissolved 
bones in agriculture, occurs in vol. iv. of the ' Journal ' of the 
Society for 1843, in a " Report by the Committee of the Moray- 
shire Farmers' Club appointed to inspect and report on the 
Experiments made in rearing Turnips by means of Sulphuric 
acid and Bone-dust," communicated by the Duke of Richmond. 
Amongst other particulars, I find recorded that raw bone-dust 
alone, applied at an expense of 38^. per acre, produced 11 tons 
9 cwts. 21i lbs. of turnips per acre ; whilst bone-dust, treated 
with sulphuric-acid, and applied at a cost of lis. Gc?. per acre, 
produced 13 tons 10 cwts. 214 lbs. of turnips. Similarly, satis- 
lactory results by the use of dissolved bones were obtained in 
1844 and 1845 by Mr. Williams, Mr. Geddes, and Dr. Monson, 
and reported to the Morayshire Farmers' Club, in experiments 
by Mr. Fleming of Boachan, Paisley ; in others by Mr. Finnic 
of Swanston ; and especially in the trials by Mr. Hannam, 
to whom the Council of our Society awarded a prize for his 
admirably well-conducted field-experiments, and the able and 
interesting Report which will be found in vol. v. 1845, " On 
