168 Mr. Griffin on a Charcoal Support for Blowpipe Experiments. 



for a comet, and imagining it a lunar rainbow or some gigantic meteor 

 before unheard of. It is no unapt representation of what one might 

 imagine the pillar of fire to have been which guided the Israelites of 

 old in the wilderness. As to its being a lunar rainbow, the idea was 

 preposterous, for it bears not the most remote resemblance to one, nor 

 forms the slightest segment of a circle ; besides, it happened to be 

 situated, as regards the moon, in a totally different direction from 

 that in which a rainbow would have been. Last night it was very 

 bright, the heavens being beautifully clear and unclouded, and the 

 moon not having risen at eight o'clock, her rays did not detract from 

 its brightness.** 



XXXIX. — On a New Kind of CJiarcoal Support for Blowpipe Expe- 

 riments, By John Joseph Griffin. 



Several of the most important experiments performed with the 

 Blowpipe, require the assistance of charcoal, upon which the object 

 submitted to examination, is supported in the flame. The charcoal 

 employed for this purpose should be of soft wood, well burnt, compact, 

 and free from crevices. Such charcoal is diflicult to obtain. I have 

 several times examined a sackful of charcoal, without finding above 

 half-a-dozen sticks adapted for these experiments. This circumstance 

 induced me to seek for a substitute, and having found one which seems 

 likely to prove serviceable, I think it possible that other persons accus- 

 tomed to operate with the Blowpipe, and accustomed also to feel the 

 want of suitable charcoal, may be willing to learn in what manner 

 they can easily replace it by an efiicient substitute. For this reason 

 I have drawn up the following notice. 



The Blowpipe experiments that require the assistance of charcoal, 

 may be divided into two classes : — In the first class may be named, 

 the formation of beads with microcosmic salt, the trial of fusibility 

 per se, and the roasting of the metallic compounds that contain such 

 volatile elements as sulphur and arsenic. The second class of experi- 

 ments is restricted to the fusion of minerals or metallic compounds 

 with carbonate of soda, or with soda and borax, for the purpose of 

 effecting particular combinations or of procuring their metals in tho 

 state of regulus. For these two classes of experiments, I make use of 



^^^ two different composi- 



. -^ _^=J^^^=^_ *^°^ supports the first 



\ y P'*=====4=======i====''^ Supports for Fusions^ 



L^^ J and the second Sup- 



• ports for Reductions. 



These are alike in appearance — the form and size of both being shown 

 by fig. a. Each consists of two parts, an upper or combustible portion, 

 and a base or incombustible portion. The former is the proper sub- 



