152 Roberts — Action of Reducing Agents on Iodic Acid. 



portions were collected and allowed to stand over sulphuric 

 acid solutions of HI0 3 and I 2 B , without any appreciable sepa- 

 ration of iodine. 



In order to test the solubility of the gas in aqueous solutions 

 of iodic acid, the nitric oxide was prepared in a generator con- 

 taining potassium nitrate and ferrous sulphate, the air having 

 been previously driven from the apparatus by means of carbon 

 dioxide. The gas was next passed into a Will and Varren- 

 trapp tube containing potassium iodide, and then into a Geissler 

 bulb containing the iodic acid. The experiment was made 

 several times with iodic acid of various degrees of concentra- 

 tion, and always with the same result. There was no evidence 

 of iodine being set free from the iodic acid, though the liquid 

 showed occasionally a barely perceptible tinge of yellow. 

 There was, however, a smaller amount of nitric oxide collected, 

 by two or three cubic centimeters than should have resulted 

 from the amount of nitrate used, and on two or three occa- 

 sions, an odor like that of chlorine was observed about the 

 Geissler bulb, when the apparatus was disconnected, which 

 could only be explained on the supposition that gaseous hydro- 

 chloric acid was carried over from the generator through the 

 potassium iodide. 



A later experiment in which nitric oxide was collected in a 

 tube containing iodic acid and hydrochloric acid so dilute that 

 no reaction took place between the two acids in the cold, showed 

 that under these circumstances the nitric oxide was absorbed 

 without any separation of iodine and that the liquid became 

 yellow and gave odor like that of chlorine, so that the above 

 seemed a plausible explanation of the disappearance of some 

 nitric oxide in the Geissler bulb without a simultaneous libera- 

 tion of iodine. 



Two or three experiments were then made with' the appa- 

 ratus as before but with the addition of a new absorption tube 

 containing silver nitrate to prevent the hydrochloric acid from 

 going over into the iodic acid. Still there was no evidence of 

 iodine being set free. It seemed apparent then, that the nitric 

 oxide was not .sufficiently soluble in iodic acid so that it could 

 be absorbed by simply passing it rapidly through the solution. 



To determine whether the gas was soluble upon long contact 

 with the iodic acid or not, different portions were collected in 

 U tubes closed at one end and filled with solutions of iodic 

 acid of different degrees of concentration. The gas had been 

 collected and allowed to stand over potassium iodide and 

 sodium hydroxide for from twenty- four to forty-eight hours 

 before being transferred to the U tube, in order to remove 

 completely any other oxide of nitrogen which might be 

 present. Solutions of iodic acid were used in the different U 



