129 
of Edinburgh , Session 1866-67. 
The liquid obtained by heating in the digestor a mixture of 
acetate of ethyl and an excess of baryta-water, did not contain any 
appreciable trace of copper. After these facts had been established, 
a number of experiments were made similar to those carried out for 
testing the ammonia method. The amount of baryta taken up by 
a weighed quantity of partially setherified acetic acid was found to 
be about ^th to T £oth l ess the same quantity of acid 
would have saturated when directly mixed with the standard alkali. 
This must be looked upon as a pretty satisfactory approximation in 
experiments of this kind. The method would, no doubt, give 
much more exact results if the excess of baryta was not titrated 
directly, but first precipitated by carbonic acid, and then alkali- 
metrically determined. The undecidedness of the end-reaction 
observed in titrating a weak organic acid with an alkali would thus 
be completely eliminated. I am now occupied with experiments 
in this direction. 
It was only after the greater part of the facts communicated in 
this notice had been established that I first saw Mr Wanklyn’s paper 
“On the Titration of Ethers” in the Chemical Society’s Journal. 
Mr Wanklyn uses alcoholic potash for decomposing the ethers, and 
obtains very satisfactory results. But he extended his experiments 
to such substances only which can be safely heated in an open 
flask, and which are easily decomposed by a short digestion with 
alcoholic potash. When alcoholic potash is heated to 100° C. in 
sealed glass tubes for about twenty-four hours, the glass is so strongly 
attacked that there is a regular layer of silica formed. 
I cannot conclude without acknowledging the great assistance 
which my friend Mr Cranston gave me in carrying out my experi- 
ments. 
2. On a Derivative of Meconic Acid. By Messrs James 
Dewar and William Dittmar. 
The meconic acid group of substances has always been regarded 
as peculiarly interesting. Situated, as it is, on the ill-defined limits 
of the fatty and aromatic compounds, and exhibiting interesting 
isomeric relations with other organic substances, the structure and 
derivatives of the whole group afford ample scope for theoretical 
VOL. VI. 
R 
