On the Atomic Weight of Glucinum, 



An analysis of a portion of this metal after the specific heat deter- 

 minations had been done was conducted as follows. Since aluminium 

 was absent in the oxide and could not have been introduced during 

 the preparation of the metal, the only impurities to be looked for were 

 silicon, iron, and glucinum oxide. On solution of the metal in a 

 dilute acid, the silicon would mostly remain behind in the free state, 

 but a part would be liberated as silicon hydride.* The oxide would 

 also remain undissolved as the metal had been heated up to 450* 

 in the specific heat determinations. The iron would, of course, 

 dissolve. 



29"4 mgrms. of the metal was dissolved in dilute sulphuric acid, and 

 left a minute, imponderable residue, which was estimated at 0"2 mgrra. 

 It remained floating in the liquid for some time, was light coloured, 

 and was probably glucina mixed with some ferric oxide. The iron in 

 solution was estimated by the depth of colour produced by ammonium 

 sulphocyanate, just as by the operation known as " Nesslerising " 

 minute quantities of ammonia are estimated. I believe this method 

 gives more accurate results for the estimation of very small quantities 

 of iron than the usual process with potassium permanganate. In 

 using a dilute solution of this reagent a considerable excess must be 

 added before the pink colour becomes visible, and the end point or 

 amount of excess is very difficult to determine ; whereas with 

 ammonium sulphocyanate and working under similar conditions it is 

 very easy to match the two colours and to determine accurately a 

 minute quantity of iron. The iron in the above solution of glucinum 

 sulphate was oxidised by a drop of weak bromine- water, the excess of 

 bromine boiled off, and a given volume of ammonium sulphocyanate 

 added in a Nessler cylinder. To another similar cylinder, containing 

 the same quantity of free acid and ammonium sulphocyanate and 

 made up to the same volume, was added a solution of ferric sulphate 

 containing O'l mgrm. iron per c.c. Of this solution 0*3 c.c. was 

 required, corresponding to 0'03 mgrm. iron. The composition of the 

 metal was therefore : — 



Glucinum 99*20 



G-lucina 0*70 



Iron 0-10 



100-00 



in other words, it was almost pure. Its purity was also shown by the 

 difficulty with which it dissolved in dilute acids. A small piece 

 which had been left in dilute sulphuric acid (1 : 10) over night was 

 only partly dissolved in the morning, but solution took place rapidly 

 on warming. 



# The silicon in commercial magnesium behaves in this manner. 



B 2 



