{ 30 ) 



tioncd, when they were in a ftate of fufion* 

 The firfl: and third, likewife, produced two 

 finall mafles refembling quartz, but thofe of 

 the fecond and fourth variety were fpongy. 

 It is very poiTibU that this author only made 

 his experiments on one fpecies. 



Some learned naturalifts are of opinion 

 that the garnets of Vefuvius are improperly 

 fo denominated ; firft, becaufe they con- 

 tain no iron ; fecondly, becaufe they fufe 

 with difficulty ; and, thirdly, becaufe they 

 differ in the proportionate qualities of their 

 conftituent parts from thofe of true garnets. 

 Thefe reafons, hov/ever, do not appear to 

 me fufficient to exclude them from being 

 clatled with this kind of ftones. It is true, 

 that iron is ufually contained in garnets; 

 but it is not elTential to them ; as has been 

 obferved by Bergmann, who, in tranfparent 

 garnets, found only y^ parts of this metal. 

 The abfence of iron, probably, therefore, 

 renders them fo difficult to fufe. With re- 

 fped: to their conftituent parts, the Swedifli 

 chemift (Bergmann) has obferved, that the 



principal 



