10 



Prof. T. S. Humpidge. 



II. Vapour-density of Volatile Glucinum Compounds. 



The compounds of glucinum which can be volatilised unchanged 

 are those which it forms with organic radicals and with the halogens. 

 Of the former class Cahours states* that he has prepared the ethide 

 and propide, and gives their boiling-points, but all my efforts to 

 prepare either of these compounds in a sufficiently pure state to deter- 

 mine its vapour- density were fruitless. I operated, as Cahours 

 recommends, on an excess of metallic glucinum with mercuric ethide 

 or propide in sealed tubes ; but either the tubes exploded violently, 

 always when a temperature of 135° was exceeded, or if the change 

 was successfully accomplished, as shown by the separation of metallic 

 mercury, the compound decomposed again on distilling. Mercuric 

 ethide acts on glucinum chloride, slowly at 100°, more rapidly at 130°, 

 and a considerable quantity of mercury ethyl chloride is produced, 

 which partly remains dissolved in the excess of mercuric ethide, and 

 partly separates out in the usual pearly scales. A similar reaction 

 takes place between mercuric ethide and glucinum bromide, but from 

 neither of these reactions couid a volatile compound of glucinum be 

 obtained. I hope to be able to examine these interesting reactions 

 at a later date. 



As the organic compounds of glucinum were not available for 

 vapour- density determinations, my attention was directed to the halo- 

 gen compounds. The bromide, chloride, and iodide of glucinum are 

 all volatile, and their volatility is in the order named. The first two 

 volatilise without decomposition if water and air are absent; the 

 last-named decomposes on heating. In the presence of a trace of air, 

 both the chloride and bromide decompose when heated, the latter 

 more easily than the former ; in both cases the haloid element is set 

 free. And since both these compounds corrode glass and porcelain 

 when vaporised in vessels of these substances, the determination of 

 their vapour- density is a matter of some difficulty. 



I first made some determinations in glass tubes with the chloride, 

 using Schwarz's modification! of V. Meyer's displacement method. 

 The glass was corroded, and the results were not concordant. Porce- 

 lain was also attacked. The tubes nearly always contained free chlo- 

 rine, although the experiments were done in pure dry nitrogen. It 

 was then decided to try platinum for the determination, and after it 

 had been found that glucinum chloride could be sublimed unchanged 



# " Compt. rend.," lxxvi. 

 f " Berlin Ber.," xvi, 1051. 



The obvious errors in this modification have been pointed out by Y. Meyer 

 (" Berlin Ber.," xvii, 1334). They are chiefly that a portion of the wide tube is 

 irregularly heated, and that the large boat which carries the substance takes air 

 with it in its fall into the tube. 



