OF ARTS AND SCIENCES : MARCH 28, 1865. 



479 



and the wire immediately adjacent, 

 become of a dnll red heat, when the 

 bead should be at once withdrawn, 

 and examined with the lens. It may- 

 be necessary to repeat this operation 

 several times before crystals are ob- 

 tained ; but the bead should always 

 be cool when heat is applied. Often 

 an amorphous cloud will be the only 

 result, even of repeated trials, although 

 the substance employed is quite easily 

 crystallizable ; and this is especially 

 apt to be the case when the bead is 

 too highly charged, or when heated 

 too long, the suspended matter being then so rapidly precipitated as 

 to prevent crystallization. The bead should in such cases be sub- 

 jected to the action of a powerful flame till perfect transparency is 

 obtained, and, if the first mentioned be the difficulty, a little more of 

 the flux added before again flaming. 



It seems to make little diflPerence with the earths whether the glass 

 containing them be prepared in the oxidating or reducing flame, pre 

 vious to flaming, though they are most readily dissolved at the point 

 of greatest heat; but the oxides of the non-volatile metals give the 

 best results when the bead is charged in the oxidating, and, after cool- 

 ing, subjected to the action of a fine-pointed reducing flame. One 

 advantage of using this small fine-pointed flame is, that only a portion 

 of the bead is subjected to the reducing influence ; and as the heat is 

 maintained but an instant, the portion of the glass fused is not only 

 circumscribed, but superficial, so that the reaction takes place where 

 it can easily be observed. Moreover, a devitrifying action goes on, 

 at the same time, in the unfused but reheated portion of the bead.* 

 I shall use the term " intermittent flame " to distinguish the ordinary 

 process of flaming from that just described. 



The amount of the substance used varies, of course, with the sub- 

 ject of the experiment, although the formation of striae in the glass, 



* As the method of treating beads just described in the text promises to be of 

 value, in certain of its applications, in the arts, as well as of scientific interest, the 

 author intends to secure such applications by patent, after having made some additional 

 experiments. 



