1819.) History of Anthrazothionic Acid. 43 
appears, but the whole of it is converted into ammoma, which 
unites with the sulphuric acid. The ammonia may be detected 
by pouring an excess of concentrated potash ley upon the liquid 
after the chemical action is at an end. A very strong smell of 
ammonia immediately becomes sensible, especially if heat be 
‘applied. This observation, as will be seen below, was of great. 
importance to me in forming a true notion of the nature of 
anthrazothionic acid. 
Sect.6.—Common concentrated muriatic acid likewise sepa- 
rates the acid from the salt without decomposing it ; but it is not 
quite pure, being mixed with muriatic acid. Concentrated liquid 
chlorine prepared by pouring concentrated muriatic acid upon 
chlorate of potash decomposes the salt quite in the same way as 
concentrated sulphuric acid: the sulphur is precipitated in 
yellow flocks ; but when the salt is mixed in the first place with 
chlorate of potash, and then muriatic acid poured over it, no 
sulphur separates, but it is completely converted into sulphuric 
acid, while the anthrazothionic acid is completely decomposed. 
At the same time muriate of ammonia is formed and carbonic 
acid is disengaged. 
Smoking nitric acid when poured upon the salt occasions a 
violent effervescence, nitrous gas and carbonic acid are given off, 
while the sulphur separates in substance. 
Some vegetable acids, as, for example, tartaric acid, are 
capable of separating the anthrazothionic acid from the salt, 
especially when assisted by heat. 
Sect. 7.—In no one of the decompositions performed by means 
of the different mineral acids, though they were often repeated by 
me, have I been able to perceive so much as a trace either of prus- 
sic acid or of cyanogen ina free state, though I examined both the 
liquids that came over into the receiver and those which remained 
behind in the retort. No prussian blue was ever formed when 
they were treated with ammonia and an acid solution of oxide 
of iron. Hence I consider myself as entitled to conclude with 
the greatest certainty that neither cyanogen nor prussic acid as 
such are elements of anthraxothionic acid. And this conclusion 
is not only confirmed in the fullest manner by the decomposition 
of the acid by means of the galvanic battery ; but also by the 
decompositions of the various combinations of anthrazothionic 
acid by means of heat to be related below. As Porrett affirms 
the contrary of this, there can be no doubt that he must have 
operated upon a salt containing a prussiate mixed with it. This 
would be more readily the case as he employed no alcohol, and 
indeed no method whatever to free anthrazothionate of potash 
from the prussiates. 
Sect. 8.—There are much stronger grounds for concluding 
from what has been already stated that ammonia is one of the 
immediate constituents of anthrazothionic acid ; paradoxical as 
it may seem that an alkali should constitute an element of an 
