315 



Third Report to the Royal Society Water Research 



Committee. 



By PERCY F. FRANKLAND. Ph.D., B.Sc., F.R.S., Professor of Chemistry 

 in Mason College, Birmingham, and H. MARSHALL WARD, D.Sc., 

 F.B.S., F.L.S., F.R.H.S., Professor of Botany, Royal Indian 

 Engineering College, Cooper's Hill. Presented to the Com- 

 mittee October 4, 1894. 



PART I. 



"Further Experiments on the Action of Light on Bacillus 

 anthracis, and on the Bacteria of the Thames." By H. 

 MARSHALL WARD, D.Sc.,F.R.S.,F.L.S., F.R.H.S., Professor 

 of Botany, Cooper's Hill. 



In a previous Report to the Committee, I have shown that the 

 action of light on bacteria is not only very definite, and much more 

 pronounced than had hitherto been supposed, but that it has an im- 

 portance in its bearing on the question of the destruction of these 

 organisms in the water of rivers, ponds, &c., vastly greater than had 

 ever been suspected. 



In this Report I offer some of the results of long continuous in- 

 vestigations into the details of this bactericidal action of light both 

 solar and electric and into the bacterial flora of the River Thames, 

 as studied at a point where it flows below Cooper's Hill. 



The reader may be referred to the previous Reports* for details as 

 to the methods of investigation employed, and as to the chief results 

 obtained by exposing the spores of Bacillus anthracis to the direct 

 action of undecomposed solar light ; he will also find further details 

 in two papers presented to the Royal Society in 1892 and 1893f 

 regarding this matter, and regarding preliminary investigations into 

 the action of solar light which has been passed through various 

 absorbent media. 



Special attention may be directed to pp. 23 34 of the ' Pro- 

 ceedings,' vol. 53, and the following experimental results may in the 

 first place be taken as supplementing those there published. 



* ' Proc. Roy. Soc.,' vols. 51 and 53. 



t ' Proc. Roy. Soc.,' vol. 52, pp. 393100 ; and vol. 53, pp. 2344. 

 VOL. LVI. Z 



