114 
IOWA ACADEMY OF SCIENCES. 
Four other experiments were performed consecutively 
upon the same solution with the results given below. In 
experiment (8) the solution after standing twelve hours 
was shaken for one and one-half hours, and a portion fil- 
tered off and the zinc determined. It should be mentioned 
that all the solutions after long standing smelled strongly 
of hydrogen sulphide. 
SERIES IY. 
N O . OF 
EXAMINATIONS. 
X. 
M. 
ZN IN 
SOLUTION. 
FREE Hcl . 
1 
1 
1.83 
2.82 
2 
1 
12 
1.56 
3.11 
3 
1 
m 
1 57 
3.10 
4 
3* 
m 
0.S9 
3 87 
Series III and IY are not comparable since the precipi- 
tation vessels and the volumes of the solutions were not 
the same. 
Even though the agitation seemed to have little effect 
as shown in Series IV, it seemed desirable to try a series 
of experiments to determine the effect of agitation while 
hydrogen sulphide is passing through the solution. To 
this end two solutions at the same temperature were sim- 
ultaneously treated with hydrogen sulphide flowing from 
two generators and at very nearly the same rate. In one 
of the tubes was a small stirrer. The effect seems to be a 
slight acceleration of the reaction. 
SERIES V. 
NO. OF 
EXAMINATIONS. 
TIME. 
TOTAL Hcl. 
ZN REMAINING IN 
STIRRED SOLUTION. 
ZN IN SOLUTIONS 
NOT STIRRED. 
1 
1 
4.86 
o d3 
3.65 
2 
2 
4 86 
2.85 
2 80 
3 
3 
4.86 
2.15 
2 23 
4 
4 
4 86 
1.73 
2.01 
The effect of temperature was next considered. A new 
solution of zinc containing 8.94 per cent of hydrochloric 
acid and 8.49 per cent of zinc was used, with the results 
given in Series VI. 
