WARINGTOS O N THE SOLUBILITY OF BONE-ASH 80 X-01~ the Solubility qf tlie Pliosphntes of Eone-Ash iii C'trd~oitic T a t e r . By ROBEXT WARISGTOX. IN the year 1866 I brought before the Society some results of an investigatioii into the solubility of tricalcic phosphate under various conditions wliicli might be supposed to occur in soil.* The results described in that paper 7vcre obtained with pure salts artificially pre- ptred. It TWS intended in the nest placc to examine tlie various natural mixtures which form tlie phosphates arnilnblc for agriculture aiid to ascertaiii them solnbility under siinilay conditions The invcsti- p t i o i i of this sccoiid part of tlie subjcct mas conimencccl a t the Ropd Agricultural College during tlie spring of 1867 but n as soon after- wards unnvoiclably relinquishecl.Hnring no prospect of completing the experiments I desire to put on record the results then obtained. Two specimens of hone-ash were tlic pliospliates examined-one n cominercial samplc of unknown history and fhir average qnality the othcr a sample nf pure bone-ash from Roiliamsted liii~dly furnished by Mr. Lawes representing the carcass bones of an entii-e os. These speciniciis of bone-ash Tere analysed ~ ~ i t l i the following results :- Pure Ox Bone-ash. C'omniercid Bono-ash. 1.86 Moisture and volatile matter 6.70 9.69 Siliceous mitter .5s .51 .17 52.46 1.02 Magnesia Pliosphoric acid Oxide of iron Lime 43.37 1.14 33.68 Carbonic acid alldies ancl other sub- stances undet'ermined 4.84 100~00 30.55 4.43 100.00 A preliminary experiment was made with the commercia1 bone-ash.An unknown quantity? T T ~ S treated with mater and carbonic acid passed into the mixture the end of the delivery-tube being so placed that the passage of thc gas kept the bone-ash in suspension. After fivc days the solution was rcmoved and analysed. The results were most unexpected. Ten thousand parts of the solution contained 2.495 P20, a degree of solubility equal to that of gelatinous tricalcic phosphate in carbonic water. A large quantity of magnesia was also * Jonr. Cham. Soc. 1866 rol. iv 11. 296. f In tliia case the bone-ash was mall washed with hot water before the eaperi- ment commenced. This was not doue in the snbsequent experiments.IN CARBONIC VATER. From this first trial it appeared rery probable that x part of tlie phosphoric acid in bone-ash existet1 in a coniparativcly soluble form since it was most milikely that the high degree of solubility just mcn- tioned \.vonld be sustained during snccessive trentnicnts with carbonic water. I n order therefore to asoertain the pmnn~cirt solubility of the phosplixtes of bone-ash 400 grains nf the commercial boiie-ash were placed in a pint bottle and subjectecl t o rc1icatcd trcatrncd mifh water and carbonic acid each solution of bonc-ail1 h i i g removed by dccan- tation and aiinlysed while thc residue Was SllbJCCtell afresh to tllc process of solution tlie intention being to contiinie this mode of pro- ceeding until the amount of pliosphoric acid removed ccascd to vn~y.A similar series of solutions WRS macle witli thc purc bonc-ash ; but i t having been fouiid that the solnbility clccrenscd very slowly in tlie earlier series of experiments only 3C)f) grains of this bonc-ash vcre operated on. I n every case the carbonic water rcrnainecl in coutact fir three or more clays during which gas was pnssed for 1 G to 24 hours. The results obtained are shomn in the following tablus :- SI To td dissolved Total d i s s o l d __ fix 100 1 originally I. Eqieriiiieiits on flw Solubility of Omz~ne~cbiI Boiae-mh. Found in 10,000 parts of each solution. Foulid in 10,000 p u t s of each solution. h-umber of I. 11. solution. I 1 If - - PZOj *.1,010 ,634 coo 1.376 1'188 MgO ,. 2.382 '526 * Determined with uranium t where determinations were wanting an estimate has hcen introdutcd in ciilcn- lating this number. WARISGTOS ON THE SOLUBILITY OF BONE-ASH 52 Between esperimciits T I and TI1 with conimercial bone-ash and between elperimcnts IV and V with pure bone-asli the nuidissolved phosphates were reniovecl fi-om the bobtle aiid recliiced to the finest po wclcr obt niiiablc. 111 thc first series of experiments thcre is a gradual clecliiie in the amount of pliosphoric acid dissolved aiid the figures give no evidence that the miiiiiniim solubility was reaclied eren at the end of the series. The aiiiouiit of pliospiioric acid taken up by the first solution is about three times as great as tlint clissolvecl by the fifteenth treatment with carboiiic water.T'lie real difference betn cen tlie primary and final solubility of tlic bone-aslt pliosplintes \vas probably however far greater tlim this. For siuce i t is showii by the eiperiiiieiits that only n small fi-action of ilic pliospliates possessed a liigli degree of solubility it is clear that to obhin a snturatccl solotion of tliese phosphates it TXLS necess&iry that the qiinnhty of bone-nsli sliunld bear a high relation t o the voliiuie of sul\eiit ~iliiclin fact it c l d not. The magiiesiiuni salts in the bone-ash appmr t o be niuch more soluble tlinii tlie calcium salts as incleecl \I as to be expected from previous rcscarchcs. Tlic laige ainount of magiiesia taken up by tlie hl-st solation is however very reinarliable.Thc last colunin in the table shows tliat tlie carbonic mater had on the whole rciiiovecl phosphoric acid niicl Line in the saiiie proportions as lhey existed in the bone-ash; ancl tlint about two-thirds of the magnesia had becn clissolt ed for one-ninth of tlie pliosplioiic acid ancl liinc. I n tlie series of experiments xi111 pure o s bone-ash it is at oncc evicleiit tliat thc plioapliate \\as of a much more uniform compo- sition thnn the conimeraial bone-ash used in the precediiig trials. The arnouiit of phosphoric ncicl taheii up soon fell to a minimum and remained vcry constaut to the eiicl of tlic erperimcnt though tlie amounts of lime and magnesia remorecl continued to diminish. Taking the iueaii of the last four t r d s as representing the perma- nent solubility of the phosphates of this bone-ash we have a solubility of .Ci75 PJ05 in 10,000 of carboiiic water.+ Or reckoning the plios- plioric acid as tricalcic phosphate for the sake of comparison with other results the solubility is 1 of phosphate of calcium in 6788 of carbonic watcr.Tlie table shoms that the primary snlutbility of tlie phosphates JYas mucli less in the case of the pire bone-ash tiinn in the case of the coin- mercial sample. The diiference is doubtless in part owing t o the smaller quantity of the pare bone-ash operated upon the bulk of fluid * I t will be observed tlist the permanent solubility here obtmned IS qulte near to the last solubility 111 the preceding senes.It seeins probable therefore that tlie ~ I I I I ~ U I U solubility had been almost reecherl in tho first series of experiments. IS CARBONIC WATER. S 3 remaining the same in b3th cases. This fact Iion-cwr can cxpliiin but a sinal1 part of the diffwence ~ h i c l i must) he nixiiily clue t o {#lie more uniform clinrnctcr of the p i r e lione-ash. On coinp:triug ilie analyses of the two 1i:lnc-ashes alrcady quoted the only markcc1 diffcr- ecce wliicli nppenrs is the €ai larger anioaiit o r siliceous innttcr in the commercial sample. It seems likely tliat in t h e process" of cdcinntion the sand had to somc exteut attn8cked tlie phosphate of calcium pro- ducing silicate of calcimu ancl leaving phospliat,es less basic than those constitntfing iiormal bone-ash.If this be thc case tlic grcater primary solubility of the phosphates in the comniercinl bone-as11 was owing to t,he presence of a small portion ofconii?arnti~~lp'nci(l plios~~hnics. The high solubility of the ningncsiimi salts is ci-cx more strikingly shown with tlie pare bone-ash tiinn in thc 1irc~ioiis results. The wliole erect procliiceil by tlic cay!ionic wntcr npon tlie piire bone-ash is's!iovn by the tnb!c t o Iiare co1isistecl in the removal of but t - ~ small qiiantity of the phosphoric ncid a d lime (the latter clissolvecl in somewhat larger proportion t,haii ilia formcr) ~rliile nearly tlic whole of t>lic inagncsin was taken 1112. It is not siipposed th:tt the resnlis of tlissc cletachecl cxperimeiit,~ n,rc of cuucli importance t o the a,~ricultiiral chemist ; it is indced only from a comparison of tlie belizwionr of diffciwit plios~~liatic materials that a117 salnable conclusions are to be expected.Tlic rcsiilts sliim hnnre>-cr unrnistnknblp the vast diiTwcncc wliicli may exist between primary nncl pcrnianeiit soiul)ilit,j- of a complex bocly and point to the 11ecessit~- of operating by the niethod of successive solutions wlieii- ever the perwnnent solnbility is t o be nscertainccl. This inctliod as far as I am :tn-are has been scarcely used and tllc solubilities of natural pliosphntes and other bodies ham been tlioaglit to bc snfIicic*rltIy determined by single or inclependciit cbspcrinicnts. This plan ~vliicli is a11 that is reqiiircd with pure salts is qiiite innclmissiblc n-ii,li coiu- plex bodies ancl must freqiientljr lcnd to very crroneoiis conclusions. Dr. Voelcker observed that the circuiiistance that at first grentcy quantities of phosl1lior;c acid went into solution might be clue to the presence of a11;alis. BIoreoxrer comnicrcial bone-ash is prepared not from pure boues but fI'GIl1 s ~ i C 1 1 ns linre bccn iuisrd with clried blood $c. n-11ic11 of course ~ ~ o n l c l explain the greatcr amount of soluble phosphates. &. Gill remarlceil that in the analyses of commercial bone-ash-so called bone-saw-dust-he h c l mostlF found the albalis in the statc of chlorides. Jlr. Warington confirmed this statemelit.