244 TAGG—NOTES ON MUSEUM-METHODS 
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should be made for the expansion ¢ and contraction of the alcohol, 
and at the same time a means found by which the loss of spirit 
by evaporation—it is practically impossible altogether to prevent 
this—can be made good. Where the vessel is covered by a glass. 
lid or disk a small hole is drilled in the lid, and this hole in turn is 
covered by an ordinary microscopic cover glass, luted down with 
vaseline. This permits expansion of the spirit, and relieves the pres- 
sure on the luting of thelid. The loss of alcohol that takes place is. 
periodically made good, a small thistle funnel being used to 
introduce fresh alcohol into the vessel through the small hole 
provided. In the case of jars and bottles closed with corks, a 
hole is made in the centre of the cork and a glass tube of small 
diameter inserted. This takes the place and answers the pur- 
poses of the hole drilled in the glass disks. 
BUILDING UP OF GLASS VESSELS. 
Many of the preparations in alcohoi in the Museum are 
exhibited in vessels built up of pieces of plate-glass cemented 
together so as to form rectangular, spirit-proof boxes. These 
vessels are made as follows :—Pieces of plate-glass of good 
quality are cut the reqitisite sizes to form the sides and bottom 
of the vessel, and are then carefully ground along their edges, 
so that the component pieces, when the box is put together, 
will fit evenly against one another, leaving no cracks between 
‘the joints. A cement is prepared consisting of Nelson’s amber 
gelatine, with bichromate of potash and plaster of paris. The 
gelatine is melted and the bichromate of potash and plaster of 
paris are subsequently added, and are stirred into a fairly firm 
and homogeneous cement which is used warm. A second 
cement is also prepared, composed of 1 oz. of Nelson’s amber 
gelatine, 5 grains of bichromate of potash, and a few drops of 
glycerine. Each piece of glass is gently warmed, the plaster 
cement is applied evenly along the edges to be joined, and 
while the cement is still warm the glass is fitted in its place to 
form one of the sides or the bottom of the vessel as the case 
may 
A defnite order is observed in fitting the pieces together. 
First, the glass which is to be the back of the finished vesselis _ 
