324 BOARD OF AGRICULTURE. 



Valuation per ton of two thousand pounds : — 



268.4 pounds soluble phosphoric acid . . . $33.55 

 73 " insoluble " "... 3.65 



$37.20 



Bone-black refuse, containing from 30 to 84 per cent of 

 insoluble phosphoric acid, has been offered at from twenty- 

 eight to thirty dollars per ton of two thousand pounds, 

 which makes the price per pound of insoluble phosphoric 

 about five cents in waste bone-black. On a former occa- 

 sion I stated that coarse articles of that kind are best 

 changed into superphosphates to secure remunerative results, 

 in consequence of their application to farm-lands. Waste 

 bone-black in form of dust, if applied to soil which is rich 

 in decaying organic matter, is, however, known to produce 

 quite satisfactory results. As the rate at which a finely- 

 ground bone-black may yield, under favorable conditions, 

 its insoluble phosphoric acid to the dissolving action 

 of carbonic acid containing soil-water, is a question quite 

 frequently asked, I enter here on record the results of an 

 actual experiment of Mr. Monroe Morse of Franklin, Mass., 

 which came under my notice. Foifr pounds of bone-black- 

 dust were mixed with from ten to twelve times their weight 

 of a compost of wool-waste and loam. This mixture, for the 

 purpose of protecting it against the action of rain, &c., was 

 fi.lled into a cask, full of small holes to allow a free access as 

 well as escape of gases formed, and subsequently buried in 

 a pile of the previously described compost, which served for 

 the mixture. The cask was filled and buried on the 15th 

 of January, 1877, and its contents tested by me, at the re- 

 quest of Mr. Morse, in the beginning of March. I found 

 that from 23 to 24 per cent of the entire amount of phos- 

 phoric acid was present in the state known as reverted acid, 

 soluble in carbonic acid containing water, or a solution of 

 ammonia compounds, and thus at once available to plants. 

 Many recent experiments at home and abroad indorse the 

 practice of composting fine-ground mineral phosphates for 

 some months with fecal barnyard-manure, as a very efficient 

 course to secure, in an economical way, active phosphoric 

 acid for the successful production of our farm-crops. 



