4>32 ZINC, CADMIUM, LEAD, Sec. 



but was constantly foiled. I then prepared ni- 

 trate of silver in platinum vessels, and found that 

 it was anhydrous, and that 21 %5 grains of it were 

 just precipitated by J-5 grains of chloride of so- 

 dium ; but the jveight of chloride obtained did 

 not tally with the calculated weight. After 

 many trials to discover the cause of the discor- 

 dancy (for the chloride was always slightly de- 

 ficient) I began to suspect that the distilled 

 water which I employed might perhaps contain 

 some ammonia, sufficient to dissolve a small 

 portion of the chloride, and thus to occasion a 

 deficiency, which became perceptible in conse- 

 quence of the great quantity of that liquid with 

 which it had been washed. This induced me 

 to acidulate the water with a few drops of nitric 

 acid in my next experiment. By this addition I 

 found that the chloride of silver (as far as I 

 could weigh it) amounted to just 18-25. The 

 slight excess of chloride in the experiment of 

 Berzelius, and the still greater excess in that of 

 Marcet, the former amounting to O008 grain, 

 and the latter to 0'094 grain, I ascribe to a 

 minute portion of some muriate in the filter em- 

 ployed by these chemists. This could have no 

 effect in my trials ; because I employed just the 

 quantity of nitrate of silver that was decomposed 

 by 7%5 grains of common salt. Hence, my chlo- 

 ride was always deficient ; and I had more than 

 once given up the experiment as desperate be- 



