IN USE AT THE ROYAL BOTANIC GARDEN, 245 
laid flat on a table; the two sides are next cemented vertically 
right and left of the back glass; the third glass applied is that 
which is to be the bottom of the finished vessel; and finally the 
front glass is cemented in position. 
When the plaster cement along the joints has cooled and 
has set firm enough to allow the vessel to be taken up and 
handled without risk of the pieces falling apart—this is usually 
after a few hours—the second cement, that without plaster of 
paris, is run as a luting around the inner angles of the vessel 
and is also applied as a thin layer over the outside joints. 
That this may be done successfully the second cement should 
not be very stiff. Both cements should be applied as evenly as 
possible, as the subsequent scraping and cutting away of any 
surplus cement weakens the joints and militates much against 
the success of the work. 
The vessel is placed in a cool room oe the cement allowed 
slowly to dry for one or two days, after which it is placed in 
strong sunlight until quite dry and until the gelatine under 
the action of the light has turned a brownish colour. It is 
perhaps premature to speak of the vessels so made as per- 
manent, but there are in our Museum vessels which were built 
up thus five years ago which are to-day perfectly spirit-tight. 
Much handling of the vessels would appear to be harmful, 
for some preparations which have been frequently moved have 
subsequently leaked, and it should be noted, too, that the 
strength of the spirit within the vessel should be maintained 
at go per cent. if the vessel is to be kept spirit-proof. The 
alternate drying and wetting of the cement consequent upon an 
intermittant use of a vessel also causes the cement in course of 
time to give way and the vessel to leak. Plate-glass or heavy 
sheet-glass is used, as I find that the thinner sheet-glass is liable 
to crack under the binding strain it is subjected to as the. 
cement dries and contracts. 
The perfectly plane surface of the plate- glass, and the fact 
that a vessel can be made any required size, are the great 
advantages of the method, but owing to the cost of the ground 
plate-glass and labour of grinding the edges square, vessels so 
made are not cheaper than the cast-glass rectangular vessels 
to be obtained at the present day. 
