16 



Series F. Table VI. (1894). 



These investigations would carry an unwelcome conclusion if it 

 ■were not possible in some way to make the [jhosphoric acid in bone- 

 meal more etiecitive. The treatment, with sutiicient sulfuric acid to 

 produce superphosphate, would not help the bone-meal manufac- 

 turers greatly, for eyen then the phosphoric acid would not bring a 

 better return than lliat contained in the raw mineral phosphates. 

 Moreover bone-meal, as is well known, produces superphosphate 

 •of an undesirable pliysical character. Experiments were made to 

 determine whether it might be possible to treat bone-meal with small 

 quantities of sulfuric acid and still produce a product having approx- 

 imately the effect of a superphosphate. See page 5. Bone-meal 

 gives more promise with such a treatment than do the compact raw 

 mineral phosphates, because the porous bone absorbs the acid like a 

 sponge, and distributes it through its entire mass much more thor- 

 oughly. The last experiments were made with raw bone-meal and 

 glue-free bone-meal, which had been treated with slightly more sul- 

 furic acid than was required to produce two-lime phosphate. For 

 this operation, fine, dusty meal was not used, but a meal of about 

 the size of very small pease, which easily pulverized, so that the 

 grinding was simplified by the operation. Allowance was made for 

 lime carbonate. Sixty degree sulfuric acid was used, at the rate of 

 twenty pounds per hundred for raw-bone meal, and forty pounds per 

 hundred for glue-free bone-meal. The "dissolved bone-meals" had 

 the following composition : — 



Raw Bone-meal 12. SS percent j)hosphoric acid. 



of this 11.09 [)er cent soluble in citrate of ammonia. 

 6.32 percent " " water. 

 4.93 per cent nitrogen. 



Glue-free Bone-meal 21.81 per cent phosphoric acid. 



of this 21.09 per cent soluble in citrate of ammonia. 

 6. •'^9 per cent " " water. 

 0.89 per cent nitrogen. 



The experiments with these preparations were cari'ied on in sandy 

 soils, low in phosphoric acid, in connection with the experiments 

 with the different bone-meals in 1893, with barley, and in 1894 with 

 oats and mustard. Table VI gives the results. 



As could be seen upon examining the crushed particles of the raw 

 bone-meal which were hard and glassy, the acid had not penetrated 

 very far. On this account the full amount of the soluble i)hosphoric 

 acid was not produced. The effect was however a considerable one, 

 as the following shows : — 



