100 
MEASUREMENT OF HIGH TEMPERATURES. 
| BULL. 54. 
Results obtained by comparing divers standard elements from 1883 
to 1888 are given in the next tables. Unfortunately time-magnetic 
measurements are not feasible in our laboratory, with a degree of cer- 
Fig. 20. Standard Daniell. Scale, f. 
tainty to warrant their adoption. Nevertheless by comparing Latimer- 
Clark and Daniell standards, the respective tendencies to variation of 
which are probably of an opposite character, some corroborative in- 
formation may be obtained. In the next table the time or date of com- 
parison is given in the first column. The next" five columns contain 
data for Latimer-Clark elements, of which Nos. D, -£/, F were made by 
myself. Nos. 114 and 115 are Elliott standards. Curiously enough, the 
latter are neither as rigorously constant, nor is their internal resistance 
as small relatively as is the case in my own standards. I have reason 
to believe that one or both of the Elliott standards suffered by trans- 
portation, for in the examination made in 1887 No. 115 was found 
entirely out of order and was necessarily discarded. In the siphon 
Daniells the two jars are like those in Fig. 20, except in so far as they 
are permanently joined by a siphon. This siphon is filled with zinc 
sulphate through a small vertical tubulure during use, and emptied 
after using. With all precautions, however, it is impossible to keep 
the copper sulphate from diffusing into the zinc jar and corroding the 
metal. Hence this siphon form is inferior in efficiency to the separate 
cell form Q already described. Beetz standards 1 are also made by 
myself. Electromotive forces are given in volts. 
1 Wiedemann Ami., vol. 23, 1884, p. 402. 
(754) 
