SODA. 



the Dub. Ph. ; " precipitated chalk" of the Dub. Ph. ; and 

 « benzoic acid" of the Ed. Ph. 



The " dried fubcarbonate of foda" of the Lend. Ph. is 

 prepared by expofing lib. of fubcarbonate of foda to a mo- 

 derate heat in a clean iron vefl'el, until it becomes perfeftly 

 dry, and at the fame time Itirring it diligently with an iron 

 fpatula, and finally rubbing it into a powder. The Dubl. 

 Ph. direAs the " dried carbonate of foda" to be prepared 

 by liquefying the cryftals of carbonate of foda in a filver 

 crucible over the fire ; then, in an augmented heat, ttirring 

 the dilTolvcd fait, until by the evaporation of the water it 

 becomes dry ; reducing it to a fine powder, and preferving 

 it in Hopped phials. The conftituents of loo parts, in this 

 ftate, according to the analyfis of Kirwan, are 40.14 of 

 acid, and 59.^6 of foda. Dr. Beddoes has extolled this 

 fait in form of pills, as a remedy in calculous affeftions ; 

 and, as Thomfon fays, it certainly affords decided relief 

 from the painful fymptoms attending calculus in the kid- 

 nies, and other urinary affeftions. Its eftefts, however, are 

 only palliative, and depend on its deftroying the prevalent 

 acid in the ilomach ; and hence it cannot, in ftrict language, 

 be regarded as a lithontriptic. The dofe is from grs. x 

 to grs. XV, given three times a day. Beddoes direfted it 

 to be combined with foap and aromatics. 



The " water of fupercarbonate of foda" of the Ed. Ph. 

 is to be prepared from lolbs. of water, and 2 oz. of fub- 

 carbonate of foda, in the fame manner as the water of 

 fupercarbonate of potafs. This preparation is milder and 

 pleafanter than the water prepared with fubcarbonate of 

 potafs. It is manufaftured in large quantities, on a great 

 fcale, of a much fuperior quality to any which the apothe- 

 cary can prepare : and is in very general ufe as a cooling 

 beverage. Half a pint of it poured over two tabl^-fpoon- 

 fuls of lemon-juice, fweetened with a little fugar, forms an 

 excellent and very agreeable effervefcing draught. 



The " phoi^phate of foda" is prepared, according to the 

 Ed. Ph., by mixing 10 lbs. of powdered bones, reduced to 

 whitcnefs, with 6 lbs. of fulphuric acid, in an earthen vefiel ; 

 then adding 9 lbs. of water, and again mixing ; keeping the 

 veffel in a vapour-bath for three days ; afterwards diluting 

 the matter with 9 lbs. more of boiling water, and llraining 

 through a flrong linen cloth, pouring boiling water gra- 

 dually over it, until the whole of the acid be waftied out. 

 Set the drained liquor apart, that the impurities may fub- 

 fide, from which pour it off, and evaporate it to 9 lbs. To 

 this liquor feparated from its impurities, and heated in an 

 earthen veflel, add a warm folution of carbonate of foda, 

 until the effervefcencc ccafe : then ftrain, and fet the liquor 

 alide that cryltals may form. Thefe being removed, add 

 to the liquor, if necefl'ary, a little carbonate of foda, that 

 the phofphoric acid may be accurately faturatfd ; and dif- 

 pofe it, by evaporation again, to yield cryltals, as long as 

 thefe fhall be produced. Finally, let the cryltals be pre- 

 ferved in a wellclofcd veflel. 



The Dub. Ph. direfts to take of burnt bones, reduced 

 to powder, 5 lbs. ; fulphuric acid, 3^ lbs. Mix the 

 powder with the fulphuric acid in an earthen vcifel ; add, 

 gradually, five pints of water, and agitate tiie mixture. 

 Digelt for three days, adding from time to time more 

 water, left the materials fhould become dry, and continue 

 the agitation ; then pour over them five pints of boiling 

 water, and flrain through a Hnen rag, pouring on, at in- 

 tervals, boiling water, until all the acid be wafhed out. 

 Set the liquor apart, that the impurities may fubfide, from 

 wliich decant it, and evaporate it to one half; then add 

 3 lbs. 10 oz. of carbonate of foda, diflolved in a fufficient 

 quantity of warm water ; filter, and obtaiu cryftaU by rc- 



VoL. XXXIII. 



peated evaporation and cooling. The cryftals are to be 

 preferved in well-clofed vefFels; 



If the fait be not fufficiently pure, repeat the folation 

 and cryflallization. 



A cheaper mode of preparing this fait has been given by 

 M. Funcke, a German chemift. He adds to the matter of 

 calcined bones diffufed in water, juil enough dilute fulphuric 

 acid to faturate the fmall portion of carbonate of lime it al- 

 ways contains. Wiien the effervefcence ceafes, the whole is 

 diflolved in nitric acid, and as much fulphate of foda added 

 to the folution as of bone-aflies ufed. The whole is then 

 diftiUed, to recover the nitric acid ; and the phofphate of 

 foda is feparated from the refidue, which is a mixture of 

 fulphate of lime and phofphate of foda, by folution and 

 cryflallization. 



This fait has a purely faline tafte, refembling very much 

 that of common fait. Its cryftals are large, regular, tranf- 

 parent, rhomboidal prifms, terminated by three-fided prifms, 

 having a fpecific gravity of 1.333, *^f"^ efflorefcing on ex- 

 pofure to the air. It is foluble m three parts of water at 

 60°, and in tvifo parts of boiling water ; and undergoes the 

 watery fufion when heated. Its conftituents, according to 

 Thenard, are, in 100 parts, 19 of foda, 15 of phofphoric 

 acid, and 66 of water. Muriate of barytes, lime, and mag- 

 nefia, decompofe this fait ; and by the ftrong acids it is con- 

 verted into fuperphofphate of foda. 



Phofphate of foda is a mild cathartic, excellently adapted 

 for children, and others who have a fallidious tafte. It 

 may be given diflolved in gruel or broth, made without fait, 

 by which its tafte is very effeftually covered. The dofe is 

 from 3vj to Jij. It was introduced into praftice by Dr. 

 George Pearfon of London. 



The " fulphate of foda" is for the moft part artificially 

 prepared, and chiefly in the large way, during the manu- 

 facture of fal ammoniac from fulphate of ammonia and com- 

 mon fait. The directions given for preparing it, in the 

 Lond. Ph., are as follow : Take of the fait which remains 

 after the diftillation of muriatic acid, 2 lbs. ; boiling water, 

 25 pints. Diflblve the fait in the water ; then add gra- 

 dually as much fubcarbonate of foda as will faturate the 

 acid. Boil the folution until a peUiclc appears ; and after 

 having filtered it, fet it apart to cryfiallize. Pour the 

 water from off the cryftals, and dry tliem on bibulous paper. 

 The " fulphate of foda" of llie Edinb. Ph., formerly 

 " Glauber falts," (fee Glauber Sti/t,) is formed by dil- 

 folving in water the acidulous filt, which remains after the 

 diftillation of muriatic acid, and having mixed witli it car. 

 bonate of lime (chslk) in powder, to remove the fuper- 

 fluous acid, fetting it apart until the impurities fubfide ; 

 tlien, having poured off the liquor, filterini; it through 

 paper, and reducing it by evaporation, that it may cryf- 

 tallize. The Dub. Ph. direfts to diffolve the fait, which 

 remains after the diftillation of mtiriatic acid, in a fufficient 

 quantity of boiling water ; then to evaporate the filtered 

 folution to a proper point, and fet it apart, that, as it llovvly 

 cools, cryftals may be formed. Tiie tallc of this fait is at 

 firfl fimply faline, but afterwards very difagrceably bitter. 

 Its cryltals are tranfparent, fix-lided, irregular, channelled 

 prifms, with dihedral lumniits ; elflorcfcent, and falling to 

 a white powder, when expofed to the air. It is folublo in 

 2.86 parts of water at 60^^, and 0.8 of boiling water j un- 

 dergoes the watery fufion when heated, and in a llrong heat 

 is partially decompofed. According to Kirwan, ico parts 

 contain 23.52 of acid, 18.48 of alkali, and 58.00 of water ; 

 and in the dried flate, ot 56 of acid, and 44 of water. 

 Tliis fait is a very common and ufeful purgative ; but, on 

 account of it> iiauleous tafte, is not very generally pre- 

 I i fcribcd 



