On Loaded Lines in Telephonic Transmission. 313 



Nitrate and Thiocyanate.— -These salts were found to have 

 an accelerating effect. With nitrate the reaction was some- 

 what irregular, and the gas evolved was found to contain 

 nitric oxide. In the case of thiocyanate, hydrogen sulphide 

 was produced in considerable quantity. The results, con- 

 sequently, are of no value. 



Finally, two experiments were made, with acetic acid, and 

 with a mixture of acetic acid and potassium chloride ; for 

 according to the theory, presence of chloride should have an 

 accelerating effect. The acetic acid solution was that ^ of 

 maximum conductivity, and the potassium chloride solution 

 was 3*9 molar. The' action was very slow and the curves 

 obtained were irregular. In 30 hours 18 c.c. of hydrogen 

 were evolved when acetic acid alone was used, and in the 

 same time 22 c.c. of hydrogen with a mixture of 2 c.c. KC1 

 and 60 c.c. of acetic acid. 



These experiments must be regarded as rough preliminary 

 observations, and we wish to return to the subject at a later 

 date. 



Summary* 



1. The influence of chloride, bromide, nitrate, acetate, 



chlorate, and thiocyanate, in varying concentration, on 

 an aluminium anode in sulphuric acid was investigated. 



2. A theory to explain the results was brought forward and 



tested experimentally. 



3. The essential peculiarities of. an aluminium anode were 



reproduced by means of a platinum anode and a film of 

 aluminium hydroxide. 



4. Some measurements were made to determine the influence 



of chloride and of bromide, on the reaction between 



aluminium and sulphuric acid. 



Chemical Laboratory, 



University of Edinburgh. 



October 1902. 



XXX. On Loaded Lines in Telephonic Transmission. 

 By George A. Campbell*. 



[Plates V. & VI.] 



I^HE loaded line discussed in this paper is an electrical 

 circuit of two long parallel conducting wires having 

 self-induction coils inserted at regular intervals. An ele- 

 mentary mathematical treatment adapted to engineering 



* Communicated by Prof. Trowbridge. 



