W. G. Mixter — Polymerization of Oxides. 27 



after remaining a year and a half in a rubber-stoppered bottle 

 the loss was 11*6 per cent. It is marked A 2 . The substance 

 was free from chlorine. Preparation B was made from Kahl- 

 baum's ferric hydroxide, having the composition approximating 

 to Fe(OH) 3 , by heating for three days at 200-230. It contained 

 a little chlorine and lost on ignition 1-9 per cent. Next an 

 attempt was made to dehydrate ferric hydroxide at 100° 

 by the well-known method of boiling. For this purpose an 

 excess of ammonia was added to a boiling solution of ferric 

 chloride in a flask connected with a reflux condenser and the 

 boiling over a Bunsen burner was continued eight days. The 

 solution, of course, became slightly acid. A portion of the pre- 

 cipitate was washed by decantation until it became a slime and 

 ceased to settle. Then some ammonium nitrate was added to 

 coagulate it and the washing was continued. Finally the pre- 

 cipitate was collected on a filter and dried at 100°. It was free 

 from ammonia, but contained a trace of chlorine. It lost on 

 ignition 2*7 per cent. The preparation is designated as C. 



The dehydration just described may be due to contact with 

 the glass, which was above the temperature of the boiling 

 solution. One experiment made supports this view. Ferric 

 hydroxide was precipitated as before and the flask containing 

 it was surrounded by steam for eight days. The solution 

 became acid as before. The precipitate was washed, dried at 

 100°, and then digested with ammonia to break up oxychloride 

 present and washed again. Finally it was dried, pulverized 

 and heated in a weighing bulb for 21 hours at 100°, losing 

 0*1 per cent the last 12 hours. This preparation lost on igni- 

 tion 9-27 and 9-32 per cent. 



Preparation D was made from Kahlbaum's ferric hydroxide, 

 which was in the form of fine grains. It was washed with hot 

 water, digested with ammonia and washed again with hot 

 water. Next the substance was dried at 100°, sifted, and only 

 the fine powder used. A portion of the powder, after heating 

 at 100° to expel hygroscopic moisture, lost on ignition 6 - 2 per 

 cent. The remainder of the powder, 58 g., was heated four 

 days at about 160°, losing the last day - 08 g. This prepara- 

 tion lost on ignition 2 - 65 and 2 - 61 per cent. It contained no 

 chlorine. 



In a former paper* it was shown that 1 g. of ferric oxide 

 which has been subjected to a dull red heat reacts with sodium 

 oxide to form sodium ferrite with a heat effect of 363 cal. 

 Hence, after finishing the work on the various samples contain- 

 ing water, it seemed desirable to learn whether ferric oxide 

 which had been exposed to a higher temperature than a dull 

 red would give a different result than the one given above. 



* This Journal, xxxvi, 55. 



