10 THE ATOMIC WEIGHTS OF 



consisted of silver hydroxide. 8 That traces of sodium hydroxide 

 should have been carried into the receiver seemed unlikely, for 

 special precautions were observed in the distillation. Ammonia, 

 however, might have been introduced from the caustic soda, which 

 may contain (and was found to contain) traces of this substance. 

 The silver nitrate test seemed extremely delicate. It will be 

 recalled that Nessler's test can not be applied in the presence of 

 alcohol, and indicators (with the possible exception of methyl 

 orange) did not show any perceptible alkalinity of the alcohol. 



The trace of free ammonia, though probably unobjectionable 

 in the present case, was removed in the following manner: An 

 aliquot portion of the methyl alcohol was diluted with more water 

 and mixed with a few drops of very dilute hydrochloric acid until 

 methyl orange, the indicator, showed a slight acidity. The main 

 portion of the alcohol was then mixed with the required amount 

 of the same acid and distilled; a considerable portion, however, 

 was allowed to remain behind and was rejected. The distillate 

 was boiled for a long time, under a reflux condenser, with sodium 

 hydroxide prepared from sodium and, after distillation, gave no 

 test with silver nitrate. The process was then repeated twice. 

 Finally the alcohol (distilled again from pure sodium hydroxide) 

 was fractionated with a Hempel column, boiled with lime for 

 several days, and distilled. The resulting product still contained 

 almost 1 per cent, of water, as indicated by the hydrometer. As 

 the residues, to be treated with the alcohol in the quantitative 

 determinations, were never absolutely anhydrous, it did not seem 

 worth while to remove the last fraction of water from the alcohol 

 by other means. 



8 Silver hydroxide is usually referred to as a hypothetical compound which exists 

 only in solution. According to some qualitative tests, white silver hydroxide 

 may be observed for an instant when the solutions of the soluble hydroxides are 

 very dilute. It seems uncertain whether the existence of this compound has 

 merely been inferred from the properties of the corresponding copper derivative 

 or whether it has actually been identified. 



J. D. Bruce (Chem. N. 50, 208 (1884)), on mixing a dilute solution of silver nitrate 

 in 90 per cent, alcohol with an equivalent amount of caustic potash in alcohol 

 at 40 F., obtained a white precipitate, but did not succeed in separating the 

 compound unchanged. A number of papers on the properties and solubility of 

 "silver hydroxide" have been published, but it seems that such investigations 

 invariably apply to "moist silver oxide" as the initial substance. See, for 

 example, Carnelly and Walker, J. Chem. Soc. 53, 59 (1888); Bottger, Z. phys. 

 Chem. 46, 521 (1903); Whitby, Z. anorg. Chem. 67, 107; A. A. Noyes and Kohr 

 J. Am. Chem. Soc. 24, 1141 (1902). 



