ROSA AND VINAL: SILVER VOLTAMETER 479 



mental electrical unit, so that the investigations which the pres- 

 ent authors began in the summer of 1908 have passed beyond 

 the original plans in scope and duration. This has also been 

 due, in large measure, to the numerous and intricate sources of 

 error which were discovered in the course of the work, all of 

 which required painstaking investigation. 



Other experimenters who have cooperated with us at various 

 times during the course of the work are Dr. A. S. McDaniel, 

 Prof. S. J. Bates, Prof. G. A. Hulett, and Mr. Wm. M. Bovard. 

 The results of these investigations have been published in a 

 series of eight papers. 2 



A few of the principal results may be summarized as follows: 

 1. The effect of filter paper on silver nitrate solutions (whether 

 the paper is used in the voltameter itself, as has been commonly 

 done, or whether it is used in the preparation of the silver nitrate 

 solution) was shown to be serious and to result in the formation 

 of colloidal silver. This effect of the filter paper is due to the 

 formation of reducing agents from the oxycellulose of the paper 

 itself and is not due to impurities. 



2 E. B. Rosa and G. W. Vinal. Bur. Stds. Sci. Paper No. 194 (Bull. Bur. Stds., 

 9: 151. 1913); summaries in this Journal, 2: 451. 1912; Elec. World, 60: 1261. 

 1912; Elektrotech. Zs., 34: 232. 1913. 



E. B. Rosa, G. W. Vinal, and A. S. McDaniel. Bur. Stds. Sci. Paper No. 

 195 (Bull. Bur. Stds., 9: 209. 1913); summaries in this Journal, 2: 509. 1912; 

 Elec. World, 60: 1262. 1912; Elektrotech. Zs., 34: 233. 1913. 



E. B. Rosa, G. W. Vinal, and A. S. McDaniel. Bur. Stds. Sci. Paper No. 201 

 (Bull. Bur. Stds., 9: 493. 1913); summaries in this Journal, 3: 40. 1913; Elec. 

 World, 61: 84. 1913; Elektrotech. Zs., 34: 1168. 1913. 



G. W. Vinal and S. J. Bates. Bur. Stds. Sci. Paper No. 218 (Bull. Bur. Stds., 

 10: 425. 1914) ; Journ. Am. Chem. Soc, 36: 916. 1914; summary in this Journal, 

 4: 69. 1914. 



E. B. Rosa, G. W. Vinal, and A. S. McDaniel. Bur. Stds. Sci. Paper No. 220 

 (Bull. Bur. Stds., 10: 475. 1914); summaries in this Journal, 4: 52. 1914; Elec. 

 World, 63: 373. 1914; Elektrotech. Zs., 35: 789. 1914. 



G. A. Hulett and G. W. Vinal. Bur. Stds. Sci. Paper No. 240 (Bull. Bur. 

 Stds., 11: 553. 1915); Journ. Phys. Chem., 19: 173. 1915; summary in this 

 Journal, 4: 593. 1914. 



G. W. Vinal and W. M. Bovard. Bur. Stds. Sci. Paper No. 271 (Bull. Bur. 

 Stds., 13: 147. 1916); Journ. Am. Chem. Soc, 38: 496. 1916; see also this Journal 

 6: 222. 1916. 



E. B. Rosa and G. W. Vinal. Bur. Stds. Sci. Paper No. 283 (Bull. Bur. Stds., 

 13:447. 1916); see also this Journal, 6: 500. 1916. 



