72 



/. K. Phelps — lodometrie Method for the 



50 cm.' of water, which had been previously purified from car- 

 bon dioxide by boiling until one-third had been driven off in 

 steam, and kept in full, stoppered flasks until used. The acid was 

 then allowed to enter the boiling flask and the carbon dioxide 

 driven over completely to the absorption flask by boiling for five 

 minutes — the latter being shaken frequently during the pas- 

 sage of the gas into it and kept cool by standing in a dish of 

 water. The atmospheric pressure was then restored by admit- 

 ting purified air through the funnel of the boiling flask. In 

 the experiments of Table I, the inlet tube of the absorption 

 flask was closed by a rubber cap after disconnection, the exit 

 tube was attached to potash bulbs and the flask was cooled in 

 a stream of water. The exit tube was removed, a capillary 

 tube long enough to reach below the surface of the liquid 

 introduced and decinormal iodine run in until the large excess 

 of barium hydroxide had been destroyed. Then the glass stop- 

 per of the absorption flask was introduced, with a rubber cap 

 on the inlet tube and potassium iodide solution in the trap, as 

 in standardizing, and the emulsion brought to a boil. Iodine 

 was again run into the hot solution through the inlet tube 

 until the color remained distinctly red after a second boiling. 

 After cooling, the excess of iodine was determined by standard 

 arsenious acid. 



, 







Table 



I. 









CaCOa 



BaOsHs 



BaOaHs 



CO2 



Error 



Error 





taken 



taken 



found 



found 



on CO2 



Corrected 





grm. 



grm. 



grm. 



grm. 



grm. 



grm. 



1 



•0501 



•2484 



•1604 



•0227 



•0006-1- 



•0007 + 



2 



•0500 



•2381 



•1508 



•0224 



•0004 + 



•0005 + 



3 



•1022 



•3416 



•1675 



•0447 



•0003- 



•0001 — 



4 



•1026 



•3105 



• 351 



•0450 



•0001- 



•0000 



5 



•2032 



•6181 



-2692 



•0896 



•0002 + 



•0004 + 



6 



•2049 



•5761 



-2223 



•0908 



•0006 + 



•0008 + 



7 



•5088 



ri301 



-2606 



•2232 



•0007 — 



•0000 



8 



•5015 



1-0804 



•2245 



•2197 



•0010- 



•0003 — 



9 



1^0032 



2^0125 



•3004 



•4394 



•0020- 



•0006 — 







1-0064 



2^0702 



•3538 



•4405 



•0023 — 



•0009 — 



In experiments 7, 8 and 9, the barium hydroxide solution 

 was estimated by weight — in the others by volume. The cal- 

 cium carbonate used was Iceland spar in the form of chips, 

 but, though it was the best material available and considerably 

 better than the best commercial calcium carbonate at hand, 

 the test of drying below red heat and the igniting to the con- 

 dition of caustic lime with a blow-pipe, proved it to be slightly 



