chlorine. 39 



F.Penny: 35.454 (0 = 16). 



Six experiments on the conversion of silver into nitrate 

 gave 100 Ag = 157.441 nitrate ; extreme diiierence, 0.028. 

 Twelve experiments by three different methods on the con- 

 version of silver into chloride gave 100 Ag = 132.837 chlo- 

 ride. Four series of experiments on the interconvcrsion of 

 potassic chloride, chlorate and nitrate gave for the difference 

 between the molecular weights of the chloride and the 

 nitrate 26.56. Corresponding experiments with sodium 

 salts gave the same difference 26.568. The mean combined 

 with the data for the silver salts gives the molecular weight 

 of argentic chloride at 143.424, and CI = 35.454. For fur- 

 ther details see Penny's determinations of potassium, sodium, 

 nitrogen and silver. The weighings were calculated for 

 vacuum. {Phil Trans., 19.9, 1839, 32.*) 



R. Phillips : 35.688 (0 = 16). 



In order to avoid the error possibly incurred by the melt- 

 ing, of argentic chloride, etc., Phillips mixed known and 

 nearly equivalent quantities of silver dissolved in nitric acid, 

 or of crystallized argentic nitrate, with ammonium chloride ; 

 filtered, washed, and precipitated the comparatively minute 

 amount of chlorine in the filtrate with silver solution. The 

 fusion of this small quantity could cause no loss of import- 

 ance. Phillips confesses that his ammonium chloride was 

 acid and the only conclusions he draws are that CI = 36, 

 N = 14, = 8 and H = 1 may be taken without consider- 

 able error if silver is 108. [The method seems to have been 

 original and is nearly that afterwards adopted by Pelouze. 

 The acidity of the ammonium chloride would of course give 

 CI too high.] (PM. Trans., 129, 1839, 35.) 



C. Marignac : 36.001 (O = 16) ; 225.007 (0 = 100). 



Determined by passing chlorhydric acid gas over hot 

 cupric oxide and condensing the water formed. The mean 

 of three experiments was CI = 450.013 ; the extreme difi'cr- 

 ence is 0.2 for = 100. The gas was made from recrj^s- 



*This is one of the most elegant investigations of the kind to be found 

 in chemical literature, though it scarcely receives a mention except from 

 Stas, who accords to it the praise it deserves. Stas' wonderfully exhaustive 

 researches were necessary to prove beyond question that chemistry has a 

 mathematical basis, and that the atomic weights of the elements are incom- 

 mensurate. Penny's investigation, taken in connection with Stas', shows 

 that the highest degree of accuracy is not incompatible with the simplest 

 means when the}- are applied with the care and acumen, without which 

 «xact results cannot, under any circumstances, be obtained. 



