Langenhan—The Arsenical Solutions. 
173 
No. 1 
1.01 p. 
c. 
As a 0 3 
2.0 p. 
c. 
KHCO s 
No. 2 
1.01 p. 
c. 
As 3 0 3 
1.0 p. 
c. 
KHCOs 
No. 3 
1.09 p. 
c. 
As 2 0 3 
1.9 p. 
c. 
KHCOs (computed) 
As the results obtained agree with the amounts used, within the 
limit of error, 97 one of two conclusions may be offered: viz. that no 
reaction takes place between the two compounds; or that the hy¬ 
drolysis goes on during the titration until all of the arsenite is de¬ 
composed into acid and hydroxide. 
VII.) The results obtained from the assay of Fowler’s solution 
lead to the examination of some potassium arsenite of the market. 
A sample of Merck’s pure potassium arsenite was assayed with the 
following results:— 
Found Computed for K AsO a + R. 6 As0 3 
As 2 0 3 65. p. c. equiv. 49. p. c. As. 72.75 p. c. 55. p. c. As. 
KOH 45. p. c. eqniv. 31. p. c. K. 20.58 p. c. 14.3 p. c. K. 
H s O . 6.62 p. c. 
According to Merck’s Report this salt has the composition 
KAs0 2 + H 3 As 0 3 . Structurally it may be represented by:— 
/OH 
As —OH 
/ 
As \OH 
VOK 
VIII.) For a better understanding of the analytical data, the 
details of the method employed may be desirable:— 
Ten grams of crystals or liquid were dissolved in water to make 
100 mils. The alkalinity of these solutions, in ten mil titrations, 
was determined, first with phenolphthalein, and secondly with 
methyl orange. From the number of mils of N/l acid required 
with each indicator the amounts of K 2 C0 3 and KHCO s were com- 
97 Ten mils instead of ten grams were assayed. Hence the results are not 
exactly on a percentage basis. 
