Mr. Griffin <w a Charcoal Swpport for Blowpipe Experiments. 159 



stitute for the ordinary charcoal, the under portion onlj acting as a 

 crucible in which the combustible portion is contained. I shall first 

 describe the composition and formation of the supports, and afterwards 

 show the way to use them. 



The incombustible portion of both supports is made of fine pipe- 

 clay and charcoal powder, mixed in equal parts by weight, with as 

 much water, slightly thickened by rice paste, as is sufficient to form a. 

 stiff plastic mass. 



The combustible portion of the Support for Fusions consist of 



Charcoal in fine Powder, . . 12 Parts. 

 Rice Flour, .... ^ — 



Water, .... about 8 — 

 The rice is boiled in the water to form a paste, with which the char- 

 coal is afterwards mixed into a mass of the consistence of dough. 



The upper part of the Support for Reductions consists of the follow- 

 ing mixture : — 



Charcoal in fine Powder, . . 9 Parts. 

 Carbonate of Soda, crystallized, 2 — 



Borax, crystallized, ... 1 — 

 Rice Flour, . . . . J — 

 Water, .... about 8 — 



The water is boiled, the soda and borax are dissolved in it, and the 

 rice is then added to form a paste, with which the charcoal is finally 

 incorporated, and the whole well kneaded into a stiff mass. 



The mould in which these compositions are pressed to form the 



supports, is made of box- 

 wood, and consists of four 

 pieces, represented by figs. 

 A, B, C, D. 



D is a cylindrical block, 

 having a conical hole through 

 tlie centre ; A, B, C, are pestles or 

 stampers fitted to this hole. The 

 mould, D, when in use, is set upon 

 a clean surface of iron, such as a 

 Blowpipe anvil. A round ball of 

 the clay composition, ^j^ inch in diameter, is put into it, and pressed to 

 the bottom by means of the pestle A This forms a conical cup or 

 crucible similar to the under portion of fig. E, which represents a 

 vertical section of a support A round ball of the combustible com- 

 position, of either kind, J inch in diameter, is next put into the mould, 

 and pressed firmly down with the pestle B, and the pestle, before being 

 withdrawn, is gently turned round to smooth the surface of the sup- 

 port The mould is now lifted from the anvil, and the pestle C is 

 applied below to push the support out of the hole. 



