474 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
acid. This was done in the case of the samples from the alimentary 
tract to destroy any soluble organic matter that might have passed 
through the filter paper and which would later hinder the arsenic deter¬ 
minations. It was added to the check to allow for the possibility of 
arsenic being introduced through the nitric acid itself. After the acid 
was added the filtrates were evaporated to dryness on a steam bath. 
When all the samples had been evaporated to dryness, they were 
redissolved in 100 c.c. of concentrated HC1, that is to say, 100 c.c. of 
HC1 was added to each sample and also to the check. From this 
point the standard method for total arsenic determination was employed. 
In a 500 c.c. distilling flask there was placed 6 grams of cuprous chloride. 
Then, through a separatory funnel, the 100 c.c. of HC1 containing the 
sample was added and the liquid distilled down to 50 c.c. The flask 
containing the sample was washed with three more portions of concen¬ 
trated HC1-50 c. c. in each portion—and these were distilled over 
after the original 100 c. c. had distilled down to 50 c. c. The final 
distillate for each sample was 200 c. c., 50 c. c. being left in the distilling 
flask. The distillate was caught in three flasks packed in ice and the 
receiving flasks were carefully washed into a large flask so that none of 
the distilled liquid was lost. Of course, the same procedure was carried 
on for all three samples and the check. The four distillates w r ere then 
made up to 1,000 c. c. each, then filtered, and finally made up into 
100 c.. c. aliquots. The aliquots were neutralized with sodium bicar¬ 
bonate and to each aliquot was added a small amount, 2 c.c., of starch 
paste as an indicator. Then the aliquots were titrated against iodine 
and as soon as a permanent, but faint, blue color was obtained, the 
quantity of iodine needed to bring about this result was determined. 
The results of the titration w^ere as follows. 
Oesophagus aliquot.No. 1—.11 c. c. 
“ No. 2—.10 c. c. 
“ No. 3—.11 c. c. 
Honey Stomach plus Stomach aliquot.No. 1—.13 c. c. 
“ No. 2—.12 c. c. 
“ No. 3—.13 c. c. 
Intestine aliquot.No. 1—.29 c. c. 
“ No. 2—.30 c. c. 
“ No. 3—.30 c. c. 
Check (water sol.) aliquot.No. 1—.11 c. c. 
“ No. 2—.11 c. c. 
A blank was also distilled over. This consisted of 250 c. c. of 
concentrated HC1 and 6 grams of cuprous chloride. By distilling over 
200 c. c. of this blank, the writer was able to determine the arsenic 
