950 MANURES AXD MANURING 



tion of the phosphate. The higher the percentage of lime actually entering 

 into the phosphate compound, the higher the citric solubility of the phos- 

 phate. 



Fineness of grinditig affects the total citric solubility of the mineral 

 phosphates (judged by 5 extracts) to the extent of approximately 10% 

 decrease for each of the gradients : passes " 100 ", refuses "100 ", refuses 

 " 60 " and refuses " 30 " sieve. 



With one exception calcining produces a marked decrease in the 

 citric solubility of mineral phosphates. The longer the calcining continues 

 the more insoluble does the phosphate become. 



The results judged as a whole confirm the conclusion of the former 

 investigation (Part I, above quoted), namely, the worthlessness of the 

 citric test as a means of establishing the relative value to the plant of phos- 

 phate manures. Rock phosphates are quite as soluble in a 0.25 per cent, 

 hydrochloric acid solution as basic slag, and there is just as much reason in 

 favour of using a weak solution of a mineral acid for a solvent as there is 

 for using a 2 per cent, citric acid solution. According to the writer it would 

 be absurd to consider basic slag as of no agricultural value because it is 

 insoluble in water, and it is equally absurd to condemn mineral phosphates 

 because they are not so soluble in citric acid as basic slag. There can be 

 little doubt that, as a source of phosphoric acid for the plant, rock or 

 mineral phosphates are just as valuable as basic slag. 



737 - Potash in Banana Stalks and Skins. —Ellis R. H. — I. I'otash in the Banana stalk, 

 in Journal of the Society of Chemical Industry, Vol. XXXV, No. 8, pp. 456-457. I/Ondon, 

 April 29, 1916. — II, Note -on the Presence of Potash in Banana Skins. Ibid., No. 9, 



p. 321, May 5, 1916. 



I. — When making an examination of the banana stalk with a view 

 to the use of its fibre for paper-making, Mr. Ellis found the juice of the 

 stalk to be markedly alkaline. He therefore made an analysis, and found 

 a large percentage of potash, and practically no soda. Another analysis 

 was made by Mr. Hanley, of the Agricultural Department of Leeds 

 University. The figures of both analyses are reprodt;ced in Table I. 



Table I. — Composition of Stalk : 



Ellis Hanley 



In original stalk : — — 



Water ■ 91.60 % 92.70 % 



Dried matter 8.40 7.30 



Ash 2.40 1.50 



Potash 1. 14 0.90 



In dried matter : 1 



Ash 29.90 20.50 



Potash 13.73 12.35 



In the ash : 



Potash 45 90 59-IO 



The readings of this Table show that the dried matter of the ^talk 

 contains as much potash as does kainit. 



