1877.] Mr. G. Williams on Emeralds and Beryls. 



165 



II. " Researches on Emeralds and Beryls. — Part II. On some 

 of the Processes employed in the Analysis of Emeralds and 

 Beryls." By Gheville Williams, F.R.S. Received April 5, 

 1877. 



While analyzing the beryl "A" from Ireland, frequently mentioned 

 in the first part of this investigation*, so many unexpected phenomena 

 presented themselves that it was found necessary to study carefully all 

 the processes which have been published for the separation of glucina 

 from alumina. On consulting the numerous papers on the subject, 

 it became apparent that a wide difference of opinion existed among 

 chemists as to the best method of working. Among the eleven or twelve 

 methods which have been proposed for the purpose, there are three 

 which have been especially employed in the most important researches. 

 I place these below, and under each heading will be found the names of 

 some of the chemists who have used the process, the first in each case 

 being that of the inventor. 



Carbonate of ammonium. Hydrate of potassium. Chloride of ammonium. 



Vauquelin . . 1798. Vauquelin 1798. Berzelius . . 1812. 



Klaproth . . 1801. C. Gt. Gmelin. . 1840. Weeren . . 1854. 



Lewy 1857. Awdejew 1843. 



Hofmeister . 1859. Damour 1843. 



Ebelmen 1848. 



The following pages are devoted to a study of the first of these, namely, 

 the carbonate-of-ammonium process. 



The first chemist to take advantage of the solubility of glucina in 

 carbonate of ammonium, as a means of separating it from alumina, was 

 Vauquelin, who, in his earliest memoir on the beryl, in which he an- 

 nounces the discovery of glucina f, mentions the fact of its solubility in 

 a solution of carbonate of ammonium ; but at that time he separated the 

 two earths by converting the alumina into alum and removing the latter 

 by crystallization. The small proportion of alumina remaining was 

 separated by taking advantage of its solubility in a solution of hydrate 

 of potassium even when heated, whereas, under these circumstances, 

 glucina is precipitated — Vauquelin thus distinctly being the first to use 

 the process now called Gmelin's. In Vauquelin's second memoir, pub- 

 lished in the same volume of the ' Annales de Chimie,' he employed car- 

 bonate of ammonium for the purpose of separating the two earths. The 

 various chemists who followed this process for many years after Vau- 

 quelin's time appear to have used it- in its simplest form, the directions 



* Proe. Royal Society, No. 145, 1873. 



t Ann. de Ch. xxvi. 1798. The name of this journal has since been modified. 



