51 
In employing this reaction for detecting hypochlorons 
acid in the liquid which was obtained by distilling bleach- 
ing powder with a small quantity of hydrochloric or sul- 
phuric acid, Goepner could not find a trace of hypochlorons 
acid, but only free chlorine. 
I have already mentioned that he says the preparation of 
hypochlorons acid by this method is described in the books 
as if this experiment had been repeated hundreds of times. 
Now this experiment has been repeated many hundred 
times in our laboratory only. Professor Roscoe shows it 
every year in his lectures, and all our students in the course 
of their practical work perform it, and find that the per- 
fectly colourless distillate is a much more powerfully bleach- 
ing agent than freshly prepared chlorine-water. This is 
quite sufficient to show that the liquid contains hypochlo- 
rous acid. But why did Goepner fail in detecting it ? 
Perhaps it was the fault of the analytical method ? To 
decide these questions I prepared hypochlorons acid by dis- 
tilling solutions of bleaching powder with dilute nitric and 
sulphuric acid and shook the colourless distillates with mer- 
cury. In every case the brown oxychloride was formed in 
quantity and possessed all the properties which Wolters has 
assigned to it, while by shaking chlorine-water with mer- 
cury only calomel was formed. From a careful perusal of 
Goepner’s paper I was unable to find the cause of his 
failure. 
Another argument against the existence of a hypochlorite 
in bleaching powder is, according to Goepner, the following. 
The chlorine which is used in the manufacture of bleaching 
powder always contains free hydrochloric acid, and thus in 
bleaching powder more calcium chloride will always exist 
than would correspond with Gay Lussac’s formula. Now 
when bleaching powder is exhausted successively with 
