228 H.Goadbyon making wet Preparations of Animal Substances. 
Having settled the length, depth, and width for an upright box, 
the glass for the sides should be selected of sufficient substance 
for the bulk and weight of fluid the vessel is destined to contain; 
and it will frequently happen that the ends (by which I mean 
the two lengths of least di- 9. 
ameter, calling the larger 
and outer portions the sides, 
as in the annexed figure, 
9,) require to be somewhat 5 
thicker than the sides to 
other direction. A small brass square will be found of considera- 
ble importance in testing the trath of the grinding, but the most 
Severe test is that which I always resort to, namely, to wet the 
ground surface of glass as lighily as possible and place on it 4 
every part of the ground surface and form with it a +. Now, 
wipe all the glass just tested quite dry ; breathe upon the ground 
surface, and quickly apply the plate-glass—if pure, the moisture 
of the breath will be equally diffused along its surface, and the 
for several seconds from the plate-glass. If the work endure this 
test, there need be no doubt about making a permanent joint. 
Again use the iron-plate, un-cement and clean the glasses, pre- 
pare the ground surfaces of the ends and the flat surfaces of the 
sides against which the ends are to abut, with the naphtha solu 
tion ; return all the glass to the iron-plate (if small enough t0 hie 
