62 THE ATOMIC WEIGHTS, 



90.831 



90.831 



90.8297 



90.823 



90.8317 



90.8311 



90.832 



Mean, 90.8299, .0008 



The quantity of silver nitrate which can be formed from a known 

 weight of metallic silver has been determined by Penny, by Marignac, 

 and by Stas. Penny * dissolved silver in nitric acid in a flask, evapo- 

 rated to dryness without transfer, and weighed. One hundred parts of 

 silver thus gave of nitrate : 



157.430 

 157-437 

 157-458 

 157.440 



157.43 



157-455 



Mean, 157.4417, .0033 



Marignac'sf results were as follows. In the third column they are 

 reduced to the common standard of 100 parts of silver : 



68.987 grm. Ag gave 108.608 grm. AgNO 3 . 1 57. 433 



57.844 " 9 I -47 I57.40I 



66.436 " 104.592 " 157.433 



70.340 110.718 157.404 



200.000 " 3*4.894 " 157.447 



Mean, 157.4236, .0061 



Stas,t employing from 77 to 405 grammes of silver in each experiment, 

 made two different series of determinations at two different times. The 

 silver was dissolved with all the usual precautions against loss and 

 against impurity, and the resulting nitrate was weighed, first after long 

 drying without fusion, just below its melting point ; and again, fused. 

 Between the fused and the unfused salt there was in every case a slight 

 difference in weight, the latter giving a maximum and the former a 

 minimum value. 



In Stas' first series there are eight experiments; but the seventh he 

 himself rejects as inexact. The values obtained for the nitrate from 100 



* Phil. Trans., 1839. 



fBerzelius' I^ehrbuch, sth ed., 3, pp. 1184, 1185. 



t Aronstein's translation, pp. 305 and 315. 



