8M 



Intelligence and Miscellaneous Articles. 



of the bottle are cemented into the wooden cover, usually on one 

 side of the clamp ; and they pass of course through corresponding 

 holes in the caoutchouc. By making these holes somewhat smaller 

 than the diameter of the tubes, the caoutchouc contracts so closely 

 around them, that not only is any liquid which might be accidentally 

 thrown up effectually prevented from getting between the caoutchouc 

 and the wooden cover, but the necessity of cementing the tube into 

 the cover may be even dispensed with. This method is so effectual 

 and easily arranged, that I am quite convinced it will supersede the 

 use of corks in the preparation of all gases which only require the 

 application of a moderate heat and do not act upon caoutchouc. 

 Ground glass plates might of course be substituted where caoutchouc 

 is inapplicable, or a sheet of ground glass might be cemented upon 

 the lower part of the wooden cover ; but these modes would be rather 

 expensive, and the cases in which they would be required are not 

 very numerous. In small bottles the use of a clamp is not essential, 

 as sufficient pressure may be obtained by inserting two wedges of 

 wood beneath a string tied around the neck, and over the top of the 

 bottle. 



J\ .. Fig- 1- 



ANTiAAA/ivfAA 



Fig. 1. A clamp of sheet iron having a small centre of brass B, in which the 

 screw C works. D disc of wood. E sheet of caoutchouc. F glass bottle. G 11 

 glass tubes. 



I will next direct the attention of the Members to a new mode of 

 cupelling, or rather to a new form of muffle. Cupellation is an ope- 

 ration not often performed by amateurs, chiefly I believe on account 

 of the difficulty in doing it unless provided with furnaces built ex- 

 pressly for the purpose. The following plan I have found to afford 

 most accurate results, while it may be performed in almost any fur- 

 nace : — The mouths of two black lead crucibles of the same size are 

 to be ground flat, so that when applied one to the other they may 

 stand quite steady. An oblong or semicircular notch is to be cut 

 out of the mouth of one of the crucibles, and a hole is also to be 



