BULLETIN OF THE BUSSEY INSTITUTION. 189 
It is plain from the foregoing statement of Mr. Saltonstall’s expe- 
rience, that, with spent bone-black at $25 per ton, and sulphuric acid 
at 23 cents per pound, soluble phosphoric acid may be made at any 
farm at a cost per pound of 13 cents (or perhaps a little less) in cur- 
rency, plus, or minus, the difference between the cost of transporting 
the raw materials to that farm and the expense incurred by Mr. Sal- 
tonstall on this account. But the conclusion thus arrived at is almost 
absolutely identical with the result that was previously determined, 
both by the cost of importing English superphosphate, and by the 
prices of the New York dealer; namely, that, in appraising a super- 
phosphate at the present time, in this part of New England, or in any 
part of the country equally accessible to seaports, 12} @ 13 cents cur- 
rency is the utmost that can be allowed per pound for the soluble phos- 
phoric acid, that is contained in it. 
It will be noticed that Mr. Saltonstall’s experience goes far to dis- 
credit a certain prejudice against the making of domestic superphosphates 
that has latterly been current. Chemists, in particular, have, of late 
years, looked with little favor upon the manufacture of superphosphates 
at the farm. ‘They have argued, naturally enough, that a chemical 
manufacture of this kind is foreign to the farmer’s legitimate business ; 
the damage done by the drought of 1873, the field was harrowed in August of 
that year, and again sown lightly with grass seed. Very early in June, 1874, 
the whole 63 acres were treated with home-made superphosphate and nitrate of 
soda, applied at the rates of 250 and 1124 lbs. per acre. There was also applied 
to the 24-acre division of the field muriate of potash (of 82%) at the rate of 100 
lbs. to the acre, and to the 4-acre division sulphate of potash (of 60%), at the 
rate of 162} lbs. per acre. “The abundant rains of this year have started the 
grass finely. Three cows and three heifers have had the run of the field, night 
and day, during the season, as well as of an adjoining piece of old pasture 
land of about 18 acres, and four horses also have been kept upon the two 
fields fully one-third of the time. The grass on the 24-acre part getting so thick 
and high that the cattle couldn’t manage it, I put in a mowing machine; left 
as much grass standing uncut upon the ground as I could, to cover the roots, 
and July 1 housed over three tons of hay from the 24 acres which had been 
pastured till the grass was cut. My foreman and myself estimate that the 24 
acres were from a third to a half better than the rest of the field. If the 1624 
lbs. per acre of sulphate of potash on the 4 acres in 1874 was a fair offset for 
the 100 lbs. of muriate per acre on the 24 acres, then all the difference between 
the parts of the field that I know of came from the 1878 manuring.” 
“ The field adjoins that on which my experiments with potatoes [see ‘ Bussey 
Bulletin,’ page 187] were made. The soil is stony, with a free gravel subsoil, 
and very dry and leachy.” 
