On the Atomic Weight of Glucinum. 



11 



in a platinum tube in a stream of nitrogen, a platinum vessel was ob- 

 tained from Messrs. Johnson, Matthey, and Co. This platinum vessel 

 was of the usual size and dimensions of those employed for vapour- 

 density determinations by displaced air, except that the narrow tube 

 was about one-half the ordinary length. The open end of this tube 

 was firmly attached to the upper part of the usual glass apparatus by 

 well-wired caoutchouc tubing.* The substance was introduced, and 

 the displaced air measured by the method used by Meier and Craftsf 

 in their researches on the vapour-density of iodine. As a graduated 

 vessel for the reception of the displaced air, an ordinary calibrated 

 burette was used, the lower end being connected with a tube of the 

 same width by strong caoutchouc tubing. These two tubes were beld 

 in common retort- stand clips, and could be easily adjusted, so that the 

 mercury was at the same level in each. They were connected with 

 the vessel in the furnace by a narrow glass tube (1 mm. bore), and 

 the one containing the air was immersed in a vessel of water. As a 

 furnace, two of Fletcher's draft furnaces were used, placed one above 

 the other, with a wide clay cylinder between them. This gave a 

 chamber 30 cm. high and 12' 5 cm. in diameter, which could be heated 

 up to any temperature from about 400° to 800°. The temperature 

 could be kept sufficiently constant for these experiments with a good 

 gas tap. 



The platinum vessel was freely suspended in two clay crucibles, 

 placed mouth to mouth, and with a hole knocked in the bottom of the 

 upper. This served to protect the vessel from the direct action of 

 the furnace gases. The temperature was measured by a Siemens' 

 pyrometer, the porcelain tube of which was connected with platinum 

 wires to the platinum vessel. % 



With this apparatus the vapour-densities of glucinum chloride and 

 bromide were determined. Glucinum chloride was prepared in several 

 ways, but the best method was found to be that recommended by 

 Nilson, which consists in heating a few mgrms. of the metal in a 

 stream of dry hydrochloric acid in a narrow platinum tube. The 

 chloride is sublimed as near the end of the tube as possible, the con- 

 nexions removed, and a small cap fitted on the open end. The tube is 

 then cut off with a pair of scissors, so as to form a small capsule in- 

 closing the chloride. This is introduced into a well-corked glass tube 

 and w r eighed. While the preparation of the chloride was going on, the 



* During the progress of this part of my -work, I received the account of Nilson 

 and Pettersson's experiments on the vapour-density of glucinum chloride (" Berlin 

 Ber.," xvii, 987). It will be observed from the sequel that I have adopted some 

 details from them, notably the use of carbonic acid for displacement. 



t " " Berlin Ber.," xiii, 851. 



X For a description of the construction and graduation of this instrument, see 

 Appendix B. 



