204 SOLL'lilLITY OF PHOSPHOKH' OXIDK. 



OriKinal Comixjsilion after standing for — 



Com- 3 24 6 12 18 



position, liours. hours, days. days. days. 



Superphospliate alone ... i/z-l — — — — — 



1. Suj)frphosphatc and Ivai- 



nit .S.S- S.Sj X.87 cS.50 8.25 8.25 



2. Snuerphosphatc and Coral 



'Queen Guano 8. 87 8.87 8.57 ><.,^7 ii.37 8.25 



3. Superphosphate and Ches- 



terfield Guano 8.87 j .87 7.37 4.87 4.00 3.37 



4. Superphosphate and I'one 



Dust 8.87 8.87 8.87 8.87 8.62 8.62 



The guano.'^ u.sed b)' Professor Gray for his mixtures had 

 the following percentage composition : Coral 



Queen. ChestertieUl. 

 Citrate-sf)luble phosi)horic oxide . . . . 18.5 17.5 



Calcium carbonate i.i 37.9 



Iron oxide 8.8 — 



The following table shows the total percentage change in 

 each of the mixtures during the i)eri(Kls specified: 



3 24 I 2 3 



lioiM-s. hours. week, weeks. week-. 



(0) Superphosi)hate and Sul- 



pliate of Ammonia... — 1.1.^ — o.ii -j-f^ 3.=^ -r-1.27 -I-2.4- 



(b) Superphosphate and Sul- 

 phate of Potash — o..v=; — 0.35 — 0.35 -\-0.6ij -[-0.46 



(<■) Superphospliate and Kai- 



nit — 0.6c; -f-0.92 +0-6q -)-o.g2 •lo.i2 



(d) Superphosphate and Gov- 

 ernment Guano — 6.80 — n.09 — 14.07 — ^>-37 ■ — 2i.o(;» 



{e) Supcri)hos])hatc and lione 



meal —2 18 — f.84 — Q.go — 14 ^^^ — 



In this table a minus sign shows reversion, and a plus sign 

 indicates an increase upon the original amount of soluble phos- 

 phoric oxide. In Profes.sor ( iray's experiments there wa^ 

 reversion in every case, and \\\v percentages of the original 

 water-sohil)]e ])hosphoric o.xide re\erted arc shown below: 



3 24 6 12 18 



hours- hours. (la_\s. da\s. day?.. 



1. SiipcrplKisphaie and Kai- 



nit 0.0 0.0 — 4 • r ■ — 6.Q — 6.'.j 



2. Superphosphate and Coral 



(Jueen (iuano 0.0 — ^^.t, — 5.3 — 5.3 — 7.0 



3. Superphos])hale and Ches- 



terfield (}uano — ri.2 — iG.q —44.8 — .S4y — 62.0 



4. Superphosphate and lione 



Dust 0.0 0.0 0.0 — 2.^ — 2.x 



'i"he tabulated results of my analyses show that the greatest 

 reversion took ])lace in mixture (d), superj)hosphate and (Gov- 

 ernment guano, and that in tliis resi)ect the .superphosphate-bone 

 meal mixtinc (r), was not far behind. 



The results obtained from nn'xture ( </ ) , superphosphate and 

 sulphate of ammonia, are of great interest, in that thev showed, 

 after the first week, a very slight but decided increase in water- 

 soluble pho.sj)h()ric oxide. .\ further set of experiments was 



