520 TRANSACTIONS OF SECTION B. 



development of the Colonies, and I have drawn attention to the important part 

 the science of chemistry can play in the Imperial work of developing the resources 

 of our Possessions. 



No apology is needed in this place for directing attention to a subject which 

 involves a most important practical application of our science, since one of the 

 principal functions of the British Association is to bring science into close touch 

 with the problems of our national life, and to interest the general public in the 

 application of science to their solution. 



I have, however, also shown that many problems of the highest scientific 

 interest arise in connection with the investigation of these economic problems. 



The meeting of the British Association coincides this year with the celebration 

 of the Jubilee of the Coal-tar Colour Industry, and we welcome among us a 

 number of distinguished foreign chemists who have come to join in honouring the 

 great chemist Sir William Perkin, to whom the inception of this industry is due. 

 It is fitting that, as President of the Chemical Section, I should refer to this great 

 occasion in my Address, and express for myself, as well as for the chemists here 

 pi'esent, the admiration we feel for Sir William Perkin's genius and for the 

 splendid example he has set in his life-long devotion to experimental research, an 

 example from which all of us have profited who have had the good fortune to 

 come into relation with him. 



The following Papers and Reports were read : — 



1. The Electrical Discharge in Air a,nd its Commercial Application, 

 By Sidney Leetiiam and William Cramp. 



Since 1904 the authors have been engaged in developing an apparatus for the 

 production of a peculiarly active gas for bleaching and sterilising purposes, dis- 

 covered by Mr. Sidney Leetham in 1903, and now much used for flour-bleaching. 

 This work has led to a number of investigations on the electrical discharge, and of 

 its efiects on air, the results of which were given. 



The subject is divided into three sections : — 



1. The co7istruction and application of the apparatus. — This consists essentially 

 of an alternator, transformer, ozoniser, and spark-box, the latter two being in 

 series on the high-tension side of the transformer. A current of air is caused to 

 pass through these while they are excited, the general result being an extremely 

 active modification of the air supplied. 



2. The electrical 2^henomena involved. — This section includes an investigation 

 of the laws which govern the various types of electrical discharge. 



3. The chemical phenomena involved. — This section includes the results of 

 analyses, &c., of the gases used, together with an account of their action upon the 

 flour. 



Lantern slides illustrating the construction of the apparatus and the behaviour 

 of the different types of discharge were shown. 

 The authors showed that — 



(a) All the types of electric discharge behave similarly, and need similar 



means for rendering them steady. 

 (6) With a properly arranged circuit any desired type of discharge may be 



obtained, and, by proper regulation, may be caused to pass gradually 



to any other type, 

 (c) The effect of adding to the number of spark-gaps in series is to raise the 



necessary pressure, but not proportionally. Similarly one spark ^s" 



long does not require three times the pressure of one spark ■^" long. 

 ((/) A current of air impinging upon the discharge increases the pressure 



required, and sets up violent oscillations in the circuit. 

 {e) The sharper the points the lower is the required pressure. 



