ON ELECTROLYSIS IN ITS PHYSICAL AND CHEMICAL BEAPaNGS. 315- 



The bar was placed between electrodes of platinum foil, which were clamped 

 against its end-faces by means of screws ; it was then placed in a bath of paraffin 

 oil, enabling it to be heated to any desired temperature up to 135° C. 



To test for electrolytic polarisation a current of about 1 ampere was passed 

 through it from three nitric acid cells for some minutes. On stopping the current 

 there appeared a slight polarisation, not, however, exceeding 00005 volt, and there- 

 fore of an order indicating a thermo-electric rather than an electro-chemical 

 origin. 



The specific resistance was then measured by observing the fall of potential 

 between two marked points, 3'22 centimetres apart, upon the bar, and comparing 

 this with the fall of potential between the two ends of a .standard resistance coil, 

 intercalated in the same circuit. The resistance was found to diminish very 

 remarkably as the temperature was raised. Observations were made at intervals 

 of from twenty to forty minutes apart, with the following result : — 



units 



It appears that the resistance of magnetite agrees with that of carbon and 

 electrolytes in possessing a negative temperature coefficient. 



A somewhat longer and thinner bar of htematite prepared for future experi- 

 ments showed a resistance of about 108 megohm.s, which in a preliminary heating 

 fell to 81 megohms. 



The determinations were made by the author's chief assistant, Dr. R. M. 

 Walmsley. 



On the Conductivity of Mixtures of Aqueous Acid Solutions. 

 By Dr. Svante Akehenius of StocMohn. 



An abstract of a paper to appear in Wiedemann's ' Annalen,' specially made by the 

 aut/ior, and communicated throuyh Oliver Lodge. The translation of the abstract 

 made by W. N. Shaw. 



1. Methods employed. Previous authors. — Hitherto only comparatively few 

 experiments on the conductivity of mixtures of electrolytes have been made, by 

 Bouchotte,' Paalzow," Bender,' and Klein."* These experiments have moreover 

 led to no definite general results, mainly on account of the paucity of experimental 

 data. 



My experiments have been made at 25° V. in the chemical laboratory of the 

 Polytechnic at Riga on Kohlrauseh's well-known method, with the use of the. 

 telephone. 



2. Distribution of the water among solutions. — When two electrolytes are dis- 

 solved in the same water two different views of the nature of the solution may be 

 held : either all the water afl'ects the one electrolyte as well as the other, or the 



. water divides itself so that only one part of it aSects the one electrolyte and 

 only the remainder the other electrolyte. Experiments (by Ostwald) have been 

 made with acetic acid and butyric acid. Normal solutions of these acids have 

 conductivities respectively of 1-478 and 1-020. According to the second view the 

 conductivity of the mixture would be |^(l-478 + 1-020). It was found to be 1-250 

 (instead of 1-249). According to the first view the mixture would have a conduc- 

 tivity equal to the sum of the conductivities, of acetic acid at half normal strength 

 (1-119), and of butyric acid at half normal strength (0"853) ; this would give 



» C.B. tome Ixii. p. 955, 1864. 



^ PoggendorflE's Annalen, Bd. cxxxvi. p. 489, 1869. 



^ Wiedemann's Annalen der Physik U7id Chemie, Bd. xxii. p. 197, 1884. 



•• Tnavg. Diss. Wiirzburg, 1885. 



