162 



§ 94. SPECIAL METHODS OF ANALYSIS. 



PnOSPHORIC ACID IS OH IS NOT IN EXCESS OVER THE ALUMINA AND 

 FERRIC OXIDE. 



Divide the filtrate from the silica in three parts, a, b, and e. 



a. I 



1. Precipitate SO3 

 withBaCl, filter. (E.)' 



2. Precipitate P2O5; 

 together with Fe.Ca,! 

 etc.,withNH4HO,or 

 NH4HO and (NH4)a- 

 CO3, filter. (F.) 



3. Eliminate K. and 

 Na. as chlorides. 



by treat- 

 ment with 



milk of 

 lime, NH4- 

 HO and 

 (NH4)2- 

 CO3, nitra- 

 tion, evap- 

 oration to 

 dryness, 

 ignition. 

 G, 1. 



ft- 

 by evapo- 

 ration to 

 dryness, 

 ignition, 

 addition 

 of oxalic 

 acid, igni- 

 tion, solu- 

 tion in 

 water, fil- 

 tration, 



and 



ignition. 



G, 3. 



1. First add FcaCU in 

 slight excess over the Pq- 

 O5 if AI2O3 and FcsOg are 

 not already present in 

 excess (see A, 1) ; then 

 eliminate the acicL 



a. 

 by addition 



of NH4HO 



in slight ex- 

 cess, diges- 

 tion, filfra- 

 tion, solu- 

 tion of pre- 

 cipitate in 

 HNO3 and 

 precipita- 

 tion of P2O3 

 with(NH4)2- 

 M0O3. 



ILL 



ft- 

 by addition 

 of NaHO 

 until nearly 

 neutral, pre- 

 cipitation 

 with NaCa- 

 H30o(oruse 



of NH4HO 



and NH4C2- 

 H3O2 if alka- 

 lies are to 

 be determ- 

 ined in lil- 

 trate); dis- 

 solve pre- 

 cipitate in 

 HCl, precip- 

 itate P2O5 

 with mag- 

 nesia mix- 

 ture and 

 citric acid. 

 H, 3. 



2. Treat filtrate from 

 precipitate by NH4HO in 

 a or NH4C2H3O2 in /3 as 

 under a, if it is desired 

 to repeat the determina- 

 tion of alkalies. 



1. First add an accu- 

 rately titrated solution 

 of Fe2Cl6 in proper 

 quantity (sec A, 2) if 

 AI2O3 and FC2O3 are not 

 already present in ex- 

 cess over the P2O5; then 

 add Na2C03 until nearly 

 neutral, and pi'ecipitate 

 Fe,Al,P205 with NaCs- 

 1H3O2; dissolve precipi- 

 tate in HCl, divide in 

 halves, precipitate one- 

 half with NH4HO, filter, 

 ignite,and wei<^h Al,Fe, 

 P2O5. Determine Fein 

 other half with K2Mn2- 

 Og, at once, or after pre- 

 cipitation w'ith NH4HO 

 and solution in II2SO4. 

 (A.) 



2. First Filtr. — 

 {From the2)r€C. by XaCj- 

 M3O2). Concentrate and 

 precipitate Mn by CI. 

 (C.) 



3. Secdnd Filtr. — 

 {From the prec. bjj CI.) 

 Conccntrate,precipitate 

 Cawith(NH4)2C204 (D). 



4. Third Filtr.— 

 (From the fjra-. b?j 

 (^7/4)26204.) Concen- 

 trate and precipitate 

 Mg. with Naoll, PO4 

 (D). 



IL 



A LARGE EXCESS OF BOTH ALUMINA AND FERRIC OXIDE IS PRESENT. 



Divide the filtrate from the silica in three parts, a, b, and c. 



