COMMERCIAL MANURES. 217 



(if the bone be old and hard a trifle more ; if young and soft rather 

 less ; fifty per cent, is a full estimate and more than the Doctor 

 himself puts it in another place.) Of this phosphate less than half 

 is phosphoric acid,* (about forty-six per cent.) so that, as near as 

 may be, avoiding small fractions, bones contain twenty-three per 

 cent, of their weight of phosphoric acid (as I stated a little while 

 ago). Now, if one hundred pounds of bone contain twenty-three 

 pounds of phosphoric acid, one hundred and fifty pounds contain 

 thirty-four and a half pounds. If two hundred and thirty pounds 

 superphosphate contain thirty-four and a half pounds phosphoric 

 acid, what per cent, is that? If my answer is right, it is just fifteen 

 per cent., — yet he tell us " containing at least" twenty per cent. ! 

 Here is a serious falling off, but the astonishing part remains. He 

 tells us "containing at least ten per cent, soluble phosphoric acid, 

 and an equal quantity of insoluble, in addition to the phosphate of 

 lime." Why ! every particle of the phosphate in bones, whether 

 phosphate of lime or the trifle of phosphate of magnesia, has been 

 used up to furnish fifteen per cent ! There is not an atom of phos- 

 phoric acid in bone except in its phosphates, and yet he tells us 

 twenty per cent, phosphoric acid in addition to the phosphate of 

 lime ! 



All I have to say about this is, that if the facts are as he states, 

 the case more than equals a realization of the desire of the boy 

 who wanted to "keep his pie and eat it too"- — for here the pie, 

 weighing only fifteen ounces before it is eaten, weighs twenty 

 ounces "at least" after it is eaten. Ought such advice to be 

 termed judicious — or injudicious — or what ?'{' 



Permit me now to read a brief extract from a recent British 

 periodical. It reads as follows : "The development of the arti- 

 ficial manui'e trade has been most remarkable ; and, whilst 



* Known in the new nomenclature of chemistry as phosphoric anhydride: or phosphoric 

 oxide (P 5) 



t Dr. Nichols seems to have been unfortunate in bis arithmetical statements in con- 

 nection with commercial manures on other occasions ; one instance of which may be 

 named here. In a lecture before the Massachusetts Board of Agriculture, given io Flint's 

 Report for 186C-7, page 237, we read as follows : " A direct estimation of the nitrogen 

 gave in 1000 pounds of bones, 50 pounds. * * * * Hence we find they afford 

 about 20 per cent, of nitrogen in their fresh condition." The error here, ia calling a 

 twentieth part, 20 per cent , instead of 5 per cent., is so gross and palpable that any 

 careful reader would readily detect it ; and it would pass for a slip of the pen, were it 

 not that, in a book published not long subsequently, entitled "Chemistry of the Farm 

 and the Sea," consi-Jting chiefly of previously written papers, newly arranged and 

 revised, we find the same error repeated in the same words, 



