Report of Society's Meetings. 193 
by the walls, and at the same time creating the necessary chimney 
draught to take away as much as possible, the sulphurous acid gas 
often so unadvisably delivered into the boiler chimney, and that often 
only a few feet above the boiler flues ; or into the main, and by this 
means transforming a new boiler into an old one in a remarkably short 
space of time, the weight of this gas, as it leaves the sulphur-box and 
its active chemical action on iron, and steel, is so well known to us all 
that the bad effects of its subtilely entering our boiler flues needs no 
further comment. 
A most dangerous external corrosion takes place on boilers through 
their being covered with lagging which rarely, or never gets removed or 
that will not indicate a leak. If external corrosion has to be remedied 
the first cause must be dealt with direct, and removed if possible ; as 
there are no means of introducing an antidote for neutralising the 
effect. I do not know of a more unsuitable boiler lagging than the 
bricks and ashes so often met with both here and in England, espe- 
cially when the filling up is done with ashes which on the least intro- 
duction of moisture give out most active corrosive gas, all samples of 
the corrosion. The conditions to be filled by lagging for boilers are not 
only that they be good nonconductors to keep in the heat but that they 
be of such a substance as to peel off, or otherwise indicate, a leakage, 
taking place under it ; of this and its effects I may possibly with your 
permission have something more to say at a future date. 
I bring before you another example which can be examined on almost 
any estate. It is the effect of moist ashes raked out, and slacked in 
contact. Where this is practised it is no uncommon thing to see a 
boiler front which was originally three-quarters thick, reduced to half 
an inch, and some places less than three-eighths, — this always necessi- 
tates repairs, seldom costing less than $200 to $300, besides materially 
affecting the life of a boiler ; and in some cases through the water get- 
ting down into the blow-off pipe, and corroding it to such an extent as to 
cause a leakage, and thus unexpectedly run the boiler short of water at the 
expense of the estate, and the undeserved discredit of the boiler feeder. 
Discussion postponed till next meeting. 
A letter from Mr. T. C. Duggin of Berbice, in which was 
enclosed a Chart of the Upper Berbice River, was read. 
The Chart being offered for sale, the Secretary was 
directed to write and ask the owner to state its price. 
BB 
