standard, and 4 ml. of the 500 p. p.m. 

 phosphorus pentoxide standard- -this 

 gives final concentrations of ZOO p. p.m. 

 aluminum oxide, 500 p. p.m. ferric 

 oxide, 10 p. p.m. manganese dioxide, 

 700 p. p.m. calciunn oxide, and 500 

 p. p.m. phosphorus pentoxide. Then add 

 0-, 5-, 15-, 20- and 25-ml. portions 

 of the standard 2000 p. p.m. magnesium 

 oxide solution to the flasks and in the 

 same order add 0-, 2-, 4-, 6-, 8- and 

 10-ml. portions of the standard 1000 

 p. p.m. potassium oxide solution- -this 

 gives concentrations in p. p.m. of mag- 

 nesium oxide and potassium oxide, 

 respectively of; and 0, 100 and 20, 

 200 and 40, 300 and 60, 400 and 80, 

 and 500 and 100. 



Measure emission intensities for 

 each sample as follows: unknown, dis- 

 tilled water, standard judged to be 

 below unknown, distilled water, stand- 

 ard judged to be above unknown, and 

 distilled water (the value obtained for 

 distilled water is subtracted from the 

 value obtained for each unknown and 

 each standard) using a Beckman Model 

 DU spectrophotometer equipped with 

 photomultiplie r and oxy-acetylene 

 flame attachments. Spectrophotometer 

 settings for magnesium oxide and anal- 

 ysis as follows: Photomultiplie r - set 

 to null dark current; sensitivity con- 

 trol - about midpoint; wave length - 

 285.2 m mu; selector switch - 0.1; 

 phototube resistor - 10,000 megohms; 

 slit width - adjust to zero meter needle 

 on 500 p. p.m. magnesium oxide stand- 

 ard at 100 percent emission; acetylene 

 pressure - 3.5 p.s.i.; oxygen pressure - 

 9.5 p.s.i. Bracket the net emission of 

 the unknown by reading the appropriate 

 pair of standards from the prepared 

 series of standards innmediately after 

 reading the unknown. Report the con- 

 centration as percent magnesium oxide 

 on dry weight basis. Spectrophotometer 

 settings for potassium oxide analysis 

 as follows: Photomultiplie r - set to 

 null dark current; sensitivity control - 

 about midpoint; wave length - 766.5 

 m mu; selector switch - 0. 1 ; phototube 

 resistor - 10,000 megohms; slit width - 

 adjust to zero meter needle on 100 

 p. p.m. potassium oxide standard at 

 100 percent emission; acetylene pres- 

 sure - 4.5 p.s.i.; oxygen pressure - 



1 1 .0 p.s.i. Bracket the net emission 

 of the unknown by reading the appro- 

 priate pair of standards from the pre- 

 pared series of standards immediately 

 after reading the unknown. Report the 

 concentration as percent potassium 

 oxide on dry weight basis. 



Calcium oxide 



Reagents and Standards: 



1. 3N hydrochloric acid (HC 1 ) - I 

 volume of concentrated hydro- 

 chloric acid and 3 volumes of 

 distilled water. 



2. 6N hydrochloric acid (HC I) - equal 

 volumes of concentrated hydro- 

 chloric acid and distilled water. 



3. Concentrated nitric acid (HNO3). 



4. Calcium oxide (CaO) solution ( 1000 

 p. p.m.) - dry National Bureau of 

 Standards argillaceous limestone 

 sample No. la (containing 41.32 

 percent calcium oxide) at 105° C. 

 for 3 hours, cool in a desiccator 

 over calcium sulfate (CaS04) and 

 weigh 2. 4201 gms. into a 400-ml. 

 beaker. Add 25 nnl. of 6N hydro- 

 chloric acid and 12.5 ml. of con- 

 centrated nitric acid. Evaporate 

 to dryness on a hot plate at medium 

 setting and let bake 10 minutes 

 after dryness is reached. Allow to 

 cool, add 5 ml. of 6N hydrochloric 

 acid and 40 ml. of distilled water 

 and heat to near boiling. Filter, 

 letting the filtrate pass through 

 the anion exchange column and 

 catching the effluent and washings 

 in a 1000-ml. volumetric flask. 

 Fill flask to mark with distilled 

 water. 



5. Amberlite IRA 400 (OH) - anion 

 exchange resin (manufactured by 

 Rohnn and Haas Company). 



6. Anion exchange column - the col- 

 umn is made by placing a plug of 

 glass wool above the stopcock of 

 a 50-ml. buret and adding amber- 

 lite IRA 400 (OH) anion exchange 

 resin to a depth of 30 cm. in the 

 buret. (The calcium is recharged 



