4819.) History of Anthrazothionic Acid. 93 
of the four constituents in a given quantity of anthrozothionic 
acid. For this purpose, I made choice of the sulphur, because 
its weight, when it is converted into sulphuric acid, may be deter- 
mined with very great precision. Porrett has already, itis true, 
determined the proportion of sulphur in anthrazothionic acid ; 
but as my analysis of anthrazothionhydrate of copper, derived 
from Porrett’s experiments and my own observations, does not 
agree with that of Porrett, I consider it as necessary to repeat 
Porrett’s experiments in a different way. 
Sect. 23.— Five grains of white anthrazothionhydrate of copper 
prepared from acetate of copper and an alcoholic solution of 
anthrazothionate of potash, after being well dried for some days 
in a heat not sufficient to alter its colour, was well mixed with 
25 gr. of chlorate of potash, and then covered with concentrated 
muriatic acid containing a saturated solution of muniate of 
barytes. The glass cup im which this mixture was put was 
covered with a glass plate, in order to prevent any of the liquid 
from being driven out of the glass by the effervescence, and the 
cover was kept applied till all chemical action was at an end, 
even when it was assisted by a strong heat. I now added an 
additional portion of muriate of barytes and some chlorate of 
potash, and allowed the liquid to digest till the portion of sulphur 
' which -had escaped oxidation was converted into sulphuric acid 
and united with barytes. During the whole process I could 
perceive no smell of sulphurous acid, but a strong one of chlo- 
vine, of which a great superabundance was present. The 
sulphate of barytes being collected and dried weighed 8:1 gr. 
which approaches very nearly to the quantity obtamed by 
Porrett. 
But we have already (sect. 16) ascertained that 4°58 gr. of 
anthrazothionhydrate of copper contain 1-510 gr. of anthrazo- 
thionic acid. Of course, five gr. of the hydrate must contain 
1:65 gr. of the acid. Now 81 gr. of sulphate of barytes are 
equivalent to 1-11 gr. of sulphur. From this it follows that 100 
gr. of the acid contain 67-3 parts of sulphur. This comes very 
near the estimate of Porrett, according to whom the acid con- 
tains 2ds of its weight of sulphur. ‘ 
Sect. 24. Stochiometrical Estimate-—Thus we have found the 
third requisite for constructing a stochiometrical synthesis of 
the acid. From these three data; namely, 1. That in the acid 
the sulphur is to the carbon as 2°6 to 0°328 ; 2. That the azote 
and hydrogen exist in it in the same proportions as in ammonia; 
and, 3. That the acid contains 67°3 per cent. of sulphur: it is 
easy to give a stochiometrical statement of the synthesis and 
analysis of this acid. In 100 parts of anthrazothionic acid there 
are 67°3 of sulphur: the remaining 32°7 consist of the other 
three constituents of the acid ; and the proportion of carbon to 
that of sulphur is as 0°328 to 2:6. Now 2:6: 0°328 :: 67:3 : 8-49, 
which, for the sake of shortness,, 1 shall make 8:5. Thus the 
