G02 
DR. T. S. HUMPIDGB OR THE ATOMIC WEIGHT OF GLUCINUM. 
two metals, if we except the result of Ebelmen,* who is said to have obtained the 
oxide isomorphous with alumina. The volatility of its chloride, its tendency to form 
basic compounds, its stable double fluorides with potassium and sodium, as well as the 
solubility of its hydrate in caustic soda or potash, all point to analogy with alumi¬ 
nium ; while its carbonates, its double sulphate with potassium, and the greater 
simplicity of some of its double compounds when its oxide is written as a monoxide 
show similarity with magnesium. 
A correct solution of this long-vexed question can therefore be only obtained either 
from the specific heat of the element or from the vapour density of some of its volatile 
compounds. Two determinations of the specific heat have been made, as referred to 
above, but with quite contradictory results ; and, as far as I am aware, no determina¬ 
tion of the vapour-density of glucinum chloride, nor of its compounds with ethyl and 
propyl, discovered by Cahours, has yet been made. The metal used by Mr. Rey¬ 
nolds in his experiments was prepared in a platinum crucible, and was apparently 
impure. His calorimeter, or as he prefers to call it, atometer, was “ essentially a spirit 
thermometer with a test-tube sealed in the bulb.” In the absence of any detailed 
description of his apparatus, and especially of the means adopted for its graduation, 
it cannot be definitely decided whether accurate results were possible or not. M. 
Nilson used iron vessels to prepare his metal and carefully determined its composition. 
It contained 13 per cent, of various impurities, which were allowed for in calculating 
the actual specific heat of the metal. The determinations were made with Bunsen’s 
accurate and delicate ice-calorimeter. 
The researches detailed in this paper were undertaken to obtain, if possible, a purer 
metal than M. Nilson’s, and to redetermine its specific heat. The vapour-density 
of volatile glucinum compounds I hope to refer to in a later paper. 
II. Extraction of glucina. 
Of the various methods recommended for the extraction of the earth from its 
commonest mineral beryl, I shall here only allude to two. The first consists in 
decomposing the finely-powdered mineral by fusion with potassium carbonate, dis¬ 
integration of the fused mass with sulphuric acid, evaporation to dryness, to render 
the silica insoluble, concentration to separate most of alumina, as alum, and treatment 
with ammonium carbonate as in the second method. This process, otherwise a good one, 
is objectionable, because of the high temperature necessary to decompose the mineral, 
and because the fused mass is only very slowly attacked by the sulphuric acid. I have 
usually followed a different method, due to Scheffer,! which consists in decomposing 
the mineral by hydrofluoric acid. Briefly, the process is as follows :—The finely- 
powdered mineral is mixed with excess of powdered fluor spar and sulphuric acid 
* Ann. d. Cb. n. Pharm., lxxx., 211. 
f Jabres. Ber. 1859, 139. 
