66 
chemical action is as follows. When sodic borate is diluted 
with water its constituents are so far dissociated that 
the iodine acts towards the soda in the same way as 
it would towards caustic soda, sodium iodide and sodium 
iodate being the result. When however the solution is 
concentrated the boracic acid, notwithstanding its feebly 
acid power, is able to displace continuously and simulta- 
neously small quantities, of iodic and hydroiodic acid from 
combination with sodium, but these two acids cannot 
coexist in the free state ; by mutual reaction they give iodine 
and water. To test the correctness of this explanation the 
following experiment was made. Boracic acid was added 
to a solution of sodium iodide ; even after boiling some time 
the solution only acquired a feeble yellow tint, and no 
iodine vapours were given off; but on the addition of 
sodium iodate the solution soon became dull brown owing 
to the presence of free iodine, which also was given off 
along with the steam. This behaviour of iodine with sodic 
borate favours the view of the decomposition of the salt by 
dilution; it also shows the varying character of chemical 
affinity under different circumstances of temperature and 
dilution. 
Ordinary Meeting, January 12th, 1875. 
B. Angus Smith, Ph.D., F.B.S., Vice-President, in the Chair. 
E. W. Binney, F.K.S., V.P., said that at the present time 
great attention was being paid to the sewerage of towns. Our 
Corporation had brought before the public a plan for dealing 
with the flood waters of the Medlock, and it is generally 
understood that Parliament will attempt to do something to 
prevent the further fouling of streams. Both Parliament 
and Corporate bodies have been long in moving in this 
