106 
of hot water. I) D hoards which catch rain drops from un- 
protected part of roof. F part for assorting goods, &c. All 
the roof is timber and glass ; there are no slates. 
By this plan the opening for emission of steam is as small 
as can be allowed, and all the air necessary is admitted at 
the proper place, and in such quantity as may be desired. 
This roof has now been at work in summer and winter, and 
a drop has never been seen to fall from it except sometimes 
from gutter E E, and this being invariably in one place it is 
of no consequence. Except in unusually close weather, the 
whole place is quite free from condensed vapour. The men 
are all dry and comfortable, instead of being stifled with the 
hot vapour and drenched with drops as they formerly were 
before this new form of roof was tried. There are many 
details which I cannot describe here, but which I show on 
the model and drawings. Modifications would be required 
for different arrangement of becks ; but the same principle 
could always be carried out. 
A paper was also read “ On the Action of Caustic Soda on 
Ethylic and Methylic Alcohol,” by Mr. A. Mylius, commu- 
nicated by Dr. E. Schunck, F.R.S. 
Schunck’s experiments concerning the action on indigo 
blue of acetate of soda, caustic soda, and alcohol, first led me 
to examine in his laboratory the influence of caustic soda on 
alcohol and methylic alcohol in sealed tubes. 
I obtained in each case a resin, differing considerably from 
the resinous body which is obtained by boiling an alcoholic 
solution of caustic soda for some time at the ordinary pressure 
and then precipitating by an acid. This so-called aldehyde- 
resin has a different composition according to the proportion 
of acid employed in its preparation, so that I think it not 
improbable that it may be composed of two resins. Its colour 
is dark brown, and it is soluble in alkali. 
On heating the same solution for some time in sealed tubes, 
