1873.] Mr. Grreville Williams on Emeralds and Beryls. 419 



2-67. The beryl A from Ireland gave 2*66 ; and a beautiful transparent 

 yellow crystal, the locality of which is doubtful, gave 2*69, or exactly the 

 same as the emeralds from Santa Fe. 



On the Effects of Fusion upon an Artificial Mixture of Beryl Ingredients. 

 — Being desirous of trying the effects of- fusion upon an artificial mixture 

 of the same composition as that of a beryl, I made a series of careful 

 analyses of the beryl A. The results of these analyses have led me to a 

 laborious examination of the processes at present in use for the separa- 

 tion of alumina from glucina. The study of the original carbonate-of- 

 ammonia process of Vauquelin, and the modifications of Rose, Joy, Hof- 

 meister, and others, has taken twelve months of constant work ; but even 

 my earlier analyses enabled me to obtain a sufficiently close approxima- 

 tion to the composition of the beryl A. The following were the pro- 

 portions used : — 



Silica 67-5 



Alumina 18 "5 



Glucina 14 



100-0 



I did not introduce any iron or magnesia, as I regard them as accidental 

 impurities varying in amount. 



When a mixture of the above composition is exposed to the flame of 

 the oxyhydrogen blowpipe, it fuses with almost exactly the same pheno- 

 mena as with the natural beryl. It is, however, as might be anticipated 

 from the absence of iron and chromiiun, much easier to get a colourless 

 transparent bead with the mixture than with either emeralds or beryls. 

 The greatest difficulty in this respect is, of course, found with emeralds. 

 The specific gravity of the fused globules was determined with the follow- 

 ing result : — 



Specific Gravity of Artificial Amorphous Beryls. 



No. of experi- 

 ment. 



W. 



W. 



t. 



pt. 



D. 



I. 



•5774 



•3394 



o 



13 



•999430 



2-42 



or almost exactly the same as the density of native emeralds and beryls 

 after fusion. 



When a small portion of chromic oxide is added to the artificial mix- 

 ture and the whole is subjected to fusion, the resulting bead is of a rich 

 yellowish green, and in many experiments approached to the emerald 

 tint ; but, as a rule, the colour is more of a faded leaf -green ; and although 

 I have never obtained a globule of the vivid tint of a fine emerald, the 

 glasses, when well cut, are quite beautiful enough to serve as jewels. 



