322 Dr. L. Bleekrode on Electrical Conductivity [Nov. 16^ 



Table III. (continued). 



Vv inter 

 montlis. 



1870-71. 



1871-72. 



1872-73. 



1873-74. 



1874-75. 



1875-76. 



Mean. 



Semi- 

 annnal 

 mean. 





— 11 1^ 



/ 11 



—5 31 



— 1 Ol 



1 ^ on 



-pO lU 



— "1 



— 1 oo 





November ... 



— 3 26 



-3 44 



+0 11 



+0 39 



+5 27 



-4 21 



-0 52 







December ... 







-4 32 



+5 9 



+4 53 



+4 32 



-7 44 



+0 23 





> -6 6-2 

















+ 7 26 



-2 37 



+4 2 



+5 4 



+ 1 6 



-2 41 



+2 3 





February . . . 



+ 16 44 



-6 45 



4-6 12 



-1 31 



+3 10 



-0 42 



+2 51 







March 



- 5 47 



-4 27 



+0 50 



-4 12 



-2 1 



-1 42 



-2 53 



) 





Yearly means 



- 1 4 



-2 40 



+0 1 



+2 18 



+2 26 



-1 3 1 





This Table shows that we can only rely on the monthly determinations 

 to within 2' 55", even excluding the result for February 1871 ; but the 

 mean value for the whole epoch has only a probable error of 21". The 

 weekly readings that are now being taken will, it is hoped, sufficiently 

 reduce the probable error of the monthly means. 



Summing up the general results of the observations with respect to 

 the main point at issue, viz. the existence of a semiannual inequality in 

 the magnetic elements, it is satisfactory to find a complete confirmation 

 of the conclusion of Sir E. Sabine, that a nearer approach of the sun in 

 the winter months produces a very sensible increase in all the elements 

 of terrestrial magnetism. 



III. " On Electrical Conductivity and Electrolysis in Chemical 

 Compounds." By Dr. L. Bleekrode. Communicated by 

 Warren De La Rue, D.C.L., E.E.S. Received October 2, 

 3876. 



§ 1. Introduction. 



In presenting this communication to the Eoyal Society I wish to 

 state that it is only an abstract of a more extensive paper on the same 

 subject which I hope to publish shortly, and which contains an account 

 of experiments with nearly seventy substances, most of which were 

 never used before for such an investigation. I tried also nearly all 

 the liquefied gases, and a considerable time was spent in preparing 

 them for this kind of research, that was often interrupted by fearful 

 explosions. The invaluable opportunity which Mr. Warren De La Eue, 

 E.R.S., granted me some time ago to try the same compounds with his 

 very powerful battery, led to residts which I hope the Society will not 

 consider devoid of interest. 



I entered on these experiments v^-ith the purpose of establishing, if 

 possible, a relation between electrical conductivity and chemical consti- 



