172 Mr. Gr. Williams on Emeralds and Beryls. [Apr. 26, 



Found after two extractions. 



Glucina 88-44 



Alumina 10-84 



99-27 



After two extractions the alumina therefore still retained nearly 2 per 

 cent, of glucina. 



Experiment III. — Although these results seemed conclusive as far as 

 they went, I resolved to repeat the experiment with a mixture containing 

 a still greater excess of glucina, because it appeared especially important 

 in an inquiry of this kind to know the behaviour towards a solution of 

 carbonate of ammonium of glucina containing a comparatively small 

 proportion of alumina. For this purpose a mixture was taken of 

 1 gramme of glucina and 3 centigrammes of alumina ; it was dissolved as 

 usual, precipitated in the form of carbonates, of the earths, and treated with 

 100 cub. centims. of solution of carbonate of ammonium. The earths dis- 

 solved entirely at first; but, small as the quantity of alumina was, the solu- 

 tion began to get turbid in about ten minutes. The mixture was left in the 

 cold for twenty hours. The residue of alumina containing glucina was 

 then filtered off, treated in the usual manner, and weighed. The glucina 

 recovered from the solution weighed 0-9846 gramme. 



Composition of Found after 



mixture. one extraction. 



Glucina ..97-09 95-59 



Alumina . . 2-91 4-16 



100-00 99-75 



Alumina, therefore, even when mixed with glucina to the small extent 

 of 3 per cent., renders some of the latter insoluble ; this, then, is a 

 distinct answer to the question at the head of the section. 



3. With what amount of accuracy can a mixture of Glucina and Alumina 

 be separated by means of Carbonate of Ammonium ? 



The fact that alumina confers its insolubility on glucina is the cause 

 of the difficulties that have been found in the separation of the two 

 earths. We have seen that, under the conditions indicated, one treat- 

 ment with carbonate of ammonium is insufficient to dissolve the glucina 

 out from such a mixture. I wish, however, to guard myself from ap- 

 pearing to express the opinion that it would be impossible, by a modifi- 

 cation of the process, to effect the separation at one operation, as, in 

 fact, I am engaged at the present moment in an attempt to solve that 

 problem. 



In order to ascertain the number of times that it would be necessary 

 to treat the insoluble residue with carbonate of ammonium, in order to 

 extract all the glucina, the following experiments were made. 



