Studies on Alloys 
125 
1 cible and add a few drops of strong nitric acid to oxidize any 
metal reduced while burning the filter paper. Weigh as Sb204 
I and SnOg. Dilute the filtrate from the above to 200 cc., add 
I 10 cc. of ammonium acetate and 5 cc. of dilute acetic acid, heat 
i to incipient boiling and titrate with ammonium molybdate in the 
I usual way. 
I For antimony weigh out from 0.6 to 0.8 gram of the finely 
I divided alloy into a 500 cc. beaker, add 50 cc. of strong hydro- 
chloric acid, and allow to stand for some time. (In practice it 
! was found to be a good plan to let the alloy stand in cold HCl over 
i night. The disintegration into a fine powder seemed to be so 
; complete that subsequent action by means of KCIO3 was readily 
I effected.) Heat to boiling and from time to time add small 
i amounts of solid KCIO3 until all is dissolved. Cool, dilute to 
j 500 cc., add a slight excess of potassium iodide crystals and titrate 
the iodine liberated with Na2S203 in the usual way. Care should 
be taken not to add too much KI. If a precipitate forms add 
HCl until it dissolves. 
The percentage of lead present is to be calculated as described 
in another article. The antimony is to be calculated as shown 
below. The tin is then to be found by difference from the mixed 
oxides of tin and antimony. The value of the sodium thiosul- 
phate solution in terms of iodine having been found in connection 
with other work, its value in terms of antimony had to be found 
from the reaction equation: 
SbCh + 2KI = SbClg + 2I + 2KCI 
Whence 253.7 parts of I are equivalent to 120.2 parts of antimony. 
Value in iodine of i cc. of the thiosulphate solution =.xxxxx (a) 
Value in antimony of i cc. of the thiosulphate {a) X ^ ^ =.xxxxx {b) 
Weight of the alloy used = .xxxx (c) 
Volume of NagSgOs used • = .xxxx (d) 
Antimony found = (d) X (b) = .xxxx (e) 
Percentage of antimony = 100 X (e) (c) = ,xxxx 
An attempt was made to use Yockey’s method for the estimation 
of antimony, but after many trials it was abandoned as too diffi- 
cult for practical purposes. His method secures the reduction 
of the antimony to the metallic condition after separating it from 
