230 Mr. A. T. Waterman on the Positive 



Furthermore, the readings could only be taken at tempe- 

 ratures for which at such low pressures the salt must have- 

 been vaporized. If an impurity were present of low vola- 

 tility, e. g. the common salts of potassium, it would remain 

 on the strip and become active. 



In cases (a) and (b) considerable metallic silver was 

 known to be present. In (c) the distilled water alone would 

 be enough to account for an emission at 800° and over 

 (see § 6). 



2. Cuprous Chloride. 



(a) The first specimen was made by Kahlbaum, but the 

 Milt had been exposed to the air for a long time, so that it 

 was light green in colour, due no doubt to partial oxidation 

 to CuCl 2 . The salt was deposited dry on a Pt strip, of 

 mounting (a), which had been glowed up to 1000° C. The 

 melting point of Gu 2 Cl 2 is given as 434° C. 



V. H. T. M. 



156 533° 



& 1487 to B 



168 1100° 



156 1487 530° S 



168 1487 1000° 



From a single curve 



e/m. 

 358-0 



to 

 311-6 



m/H. 

 27-0 

 to 

 31-0 



413-0 

 392-8 



23-35 

 24-55 



392-0 



24-6 



405-0 



23-8 



376'8 



25-6 



387-4 

 311-6 



24-9 

 31-0 



The values of m/H by the balance method rose steadily 

 from around 27 at 530° to about 31 at 1000° and remained 

 there. The only distinct values obtained by the slit method 

 are given above. They appear to be due to Na impurity 

 — m/H = 23 — at the lower temperature. At the higher 

 the Na + value still continues with one reading of a possible 

 Cu ++ ion. There is evidently more than one kind of ion 

 involved. 



(b) A pure sample of Cu 2 Cl 2 was used for this experiment^ 

 — Kahlbaum's " znr Analyse." It was placed on a Pt 

 strip, mounted by method (b), which was used for experi- 

 ments with PtO) 2 and Agl, but which had been glowed for 

 points below 1100° C. The salt was white and semi- 

 transparent. 



V. 



H. 



M. 



T. 



870° 



e/m. 



m/H. 



205 



2460 



B&S 



to 

 1200° 



280 



34-4 



