132 
Proceedings of the Royal Society 
Daring the action we did not observe any gas collecting in the 
receiver. After the reaction the gases in the retort and condenser 
were swept into the gasometer by a current of dry hydrogen. Any 
hydrochloric acid gas was immediately absorbed by the water, and 
the residual gases were then made to pass through a series of U 
tubes filled with soda-lime, in order to estimate the carbonic anhy- 
dride by weight. Only a trace of carbonic anhydride could be de- 
tected ; nothing like a molecule was evolved. 
When the terchloride of meconyl was treated with water, hydro- 
chloric acid was produced with much frothing, and the whole dis- 
solved to an intensely brown liquid. When this action took place 
in the apparatus formerly described, large quantities of carbonic an- 
hydride could easily be detected. Many attempts were made to 
produce definite salts of the acid formed in this reaction, but without 
success. When the acid liquid was thrown upon a dialyser, the 
whole of the hydrochloric acid diffused out ; a dark brown solution 
of the acid remained. This acid solution, when boiled with strong 
nitric acid, in presence of nitrate of silver, produced chloride of 
silver, and is, therefore, a chlorinated compound. Although the acid 
is a lower derivative of meconic acid, the presence of chlorine shows 
that the three atoms of chlorine replacing the water-residues are not 
retained with equal degrees of force. The dark brown solution 
was completely decolourised by the action of sodium amalgam. 
When comenic acid was treated with pentachloride of phos- 
phorus, a chloride more intractable than that formerly described 
was obtained. 
As pyromeconic acid contains the simplest form of the charac- 
teristic nucleus of the whole group, a knowledge of the structure of 
this substance would throw great light on the constitution of the 
meconic acid series. If a careful examination be made of the gene- 
ral properties of pyromeconic acid, we can hardly characterise it as 
a real acid. No doubt salts can be formed, but with great difficulty ; 
and the fact of it not combining with the alkalies or alcohol radicals, 
shows that it bears a great analogy to pyrogallic acid. If we com- 
pare the formulae of pyromeconic and pyrogallic acids, they would 
appear to be members of a homologous series ; and as we know by 
synthesis that pyrogallic acid is trihydroxyl-benzol, the pyromeconic 
acid may be looked upon as bearing the same relation to a hydro- 
