IN USE AT THE ROYAL BOTANIC GARDEN. 243 
Jf the lid does not lie evenly on the rim of the vessel the con- 
traction of the gelatine as it dries may crack the lid. To prevent 
this a cement with more body is prepared by mixing plaster of 
paris with the gelatine. The plaster fills the interstices between 
the lid and the rim of the jar. This plaster cement is applied 
warm in the same manner as the bichromated gelatine cement, 
excess of cement on the outside in both cases being cleaned off 
with a knife after it has cooled slightly. 
Il. FIRM SEALING. 
If a firm luting is required, but one which will afterwards 
permits the removal of the lid, a difficult matter when the lutings - 
given above are employed, the following is used :— 
Gelatine, I OZ. 
Paraffin wax, } oz. 
The gelatine is melted as described in the preceding case ; to 
the melted gelatine the wax is added and also melted. The two 
are then beaten together vigorously so as to form as emulsion, 
The cement is used warm, a layer of the cement being placed on 
the rim of the vessel, and the lid as before warmed slightly 
before being placed in position. 
Ill. TEMPORARY SEALING. 
For sealing lids temporarily, and as a luting when the jar, 
is not likely to be handled, vaseline presents the advantage that 
it is clean and easily applied. It prevents, better than any other 
temporary luting I have tried, loss of spirit by evaporation and 
offers no difficulty to the ready removal of the lid should this 
become necessary. 
Either of the first two cements may be used for sealing corked 
bottles. With spirit material the bichromated gelatine has given 
excellent results. The corks are dipped in the gelatine solution 
$0 as to coat them, and when the gelatine has set the corks are 
‘driven into the bottles flush with the top of the neck, or if fitting 
too tightly to permit this they are pared down flush with the top. 
Any alcohol present is carefully dried off and the surface of the 
‘cork covered with an even layer of cement. 
