122 
J. A. Baker 
Since this iodine solution was used in the estimation of tin, its 
tin value was calculated as follows from the reaction equation: 
Therefore 
or 
SnCh + 2l 4 - 2HCI = SnCh + 2HL 
Sn : 2I :: X : c 
119 : 253.94 :: X : c 
where e is the weight of iodine in i cc. of the iodine solution, and 
V is the weight of the tin equivalent to one cubic centimeter of the 
iodine solution. Then .v = (e) X .4686. 
METHODS OF ANALYSIS. 
I. For the estimation of lead. Samples of about 0.5 gram each 
were used. The alloy was in the form of fine drillings, often 
flattened by hammering. The samples were digested in dilute 
nitric acid (sp. g. -= 1.20) on the water-bath for about 2 hours. 
The decomposition seemed to be so effected by this method of 
treatment that better results were obtained than by hurried 
decomposition at higher temperatures. When the decomposition 
seemed to be complete, the samples were removed from the water 
bath and quickly evaporated till about 5 cc. of liquid remained, 
then they were diluted with 100 cc. of water, boiled up, filtered and 
washed repeatedly with hot water. The filtrate was diluted to 
about 250 cc. with water (if the volume together with the wash- 
ings was less than that), heated to 50° to 60° and the lead was 
precipitated by adding 10 cc. of sulphuric acid (i: i). The pre- 
cipitate was allowed to settle and was then filtered and washed, 
first with very dilute sulphuric acid and then two or three times 
with pure cold water. The precipitate, without separating from 
the filter paper, was placed in a flask and dissolved with 10 to 15 
cc. of strong ammonium acetate solution. The volume was then 
made up to 250 cc., heated to incipient boiling and titrated with 
the standard molybdate solution, using tannin as an indicator. 
The results are recorded at the end of this paper, 
II. For the estimation of antimony and tin. The method here 
described is based upon that published by Mr. Low, in the article 
heretofore referred to. The finely divided alloy was weighed out 
in samples of about i gram each. They were placed in an Erlen- 
