1823.] fixing F articles ofi the Sappare, 4 IS 



superior to the former, I have substituted a mixture of water and 

 refractory clay. 



Small triangles, or slender strips, of baked clay may be used 

 in lieu of sappare, which is not at all times to be procured ; or a 

 little of the moist clay may be taken up on the end of a platina, 

 or other wire, and the object to be tried touched with it. This 

 way may be applied to pieces of the ordinary size, and supersede 

 the use of the platina tongs. 



But a proceedmg which I have only recently adopted appears 

 to deserve the preference. Almost the least quantity of clay 

 and water is put on the ve?y end of a platina wire, filed flat there. 

 With this, the particle of mineral lying on the table can be 

 touched in any part chosen ; for a moment or two it is dry, and 

 may be taken up, and put into the flame, without the clay 

 exploding, as not unoften happens when more of it is used. 

 Particles of the least visible minuteness may be thus submitted 

 to trial with the utmost facility. The contact of the particle 

 with the wire may, in general, be so managed as to be 

 extremely slight, as the slenderest point is sufficient to support 

 it. However, when the utmost heat possible is desired, a frag- 

 ment of a less conducting matter may, if deemed necessary, be 

 interposed. 



There may be cases in which the presence of the clay is objec- 

 tionable. 1 conceived that some of the body itself to be tried, 

 would, on these occasions, supply its place. Flint was the least 

 promising of any in this respect. It was selected for the expe- 

 riment. With a paste of its powder and water, pieces of flint 

 were successfully cemented to flint, and some of this paste 

 taken on the end of a wire, served, if not quite as well as clay, 

 yet very sufficiently. After several times igniting and quench- 

 ing in cold water, the reduction of very hard matters to subtile 

 powder is attended with no difficulty. 



Earth of alum would perhaps be preferable to pipe-clay for 

 making the triangles on strips, and for agglutinating objects to 

 them. It would even have the advantage over sappare of being 

 a simple substance. Some from the Paris shops acquired only 

 little solidity in the fire ; but I afterwards learned that it had 

 been obtained from alum by fire. 



Since I have been in possession of this means of so effec- 

 tually confining the subjects of examination as to be able to 

 continue during pleasure to act on them, I have directed but 

 little attention to the fusibility of matters. Quartz, whose fusion 

 has been called in question by M. Berzehus,* has seemed to be 

 quite refractory. On some few occasions when it has proved 

 otherwise, the phenomena have neither corresponded with 

 M» de Saussure's account, nor been always the same, which 



* Be Temploi du Chalumeau, p. 108. 



