220 ARRAXGIXG SHELLS. 



pasteboard, covered with white paper, so that two specimens 

 of each shell are required to show the species to advantage, 

 one side to be turned up, and another down. They must 

 be attached by the following composition; which is the same 

 mentioned at page 217 for mending shells. 



Fine Spanish whitening, 2 oz. 



Gum Arabic, 2 oz. 



Finest flour, ^ oz. 

 Ox-gall, a tea-spoonful. 



This cement may be kept in a pot in a dry state, and a 

 little warm water poured on it when required. Some prefer 

 a solution of gum arable for attaching them. The solution 

 of gum arable plain, will not, however, answer the purpose, 

 as it cracks "when the weather becomes hot, and the shells 

 are disengaged. It should therefore be made in the following 

 manner. 



Gum Paste. 



White Sugar-candy, 2 oz. 



Common Gum Arabic, 4 oz. 



Ox-gall, one tea-spoonful. 



When properly dissolved, it should be strained through 

 fine muslin or gauze, and two table-spoonfuls of starch or 

 hair-powder added to it, together with half-a-drachm of cor- 

 rosive sublimate It may then be put into an earthen-ware 

 pot or bottle, and allowed to dry. A little warm water 

 poured on it will render it lit for use in a few minutes. 



