February ii, 1909] 



NATURE 



445 



have like advantages. \'ery fine work is done by the 

 Candy filter, which dispenses with precipitants, and owes 

 its efficiency to oxidiuni, a substance with properties akin 

 to those of spongy platinum. Cheapness in working is a 

 feature of this installation (Fig. i), and the effluent is 

 certified by the highest authority to be excellent. 



Great interest has been taken of late in the ozone purifi- 

 cation processes, which are in operation at Wiesbaden, 

 Nice, Philadelphia, and elsewhere. The chief difficulty in 

 the meantime is to reduce the cost of working to some- 

 thing approaching' the outlay for mechanical filtration by 

 other means. Of the efficiency of ozone treatment there 

 can be no question. The bacteria are practically eradi- 

 cated. The filtrate is sparkling and palatable, even when 

 the raw water is very bad. Progress has been made in 

 reducing costs, and in particular the Howard-Bridge 



mucli longer period, and there is considerable saving of 

 space and of working expenses. 



\ necessary adjunct to all filtering appliances is a 

 regulator to control the speed of the flow. Filters in 

 which precipitants are employed also require a regulator 

 for adjusting the dosage to the amount of water passing, 

 and various attempts have been made to perfect an 

 appliance for this end. X'ariations in the state of the raw 

 water have also to be considered. 



In the course of distribution of the filtered water to 

 consumers, impurities creep into the mains and service 

 pipes, the chief being iron o.xide and filaments of creno- 

 thrix, and in special cases lead and its compounds ; but 

 by suitable means all these can be eliminated, and without 

 much outlay. On the whole, the application of scientific 

 method and research to the technicalities of water purifi- 



A. Rotating Cyl. 



inder. 

 B' B2. Be&riQgs fin- 

 Hollow 

 Tninniona. 



CyliDdec Sup- 

 ports. 



Support of In- 

 let Pipe. 



Support of 

 Outlet Pipe. 



system effects a saving by collecting the unused ozone 

 (see Fig. 2, d) and returning it to the incoming stream. 



Many appliances are being tested at Paris for the purifi- 

 cation of river water, and notable results are being 

 obtained from the Anderson system. The precipitant in 

 this case is iron oxide. So much as 3 grams per cubic 

 metre is taken up by the raw' water in traversing cylinders 

 charged with scrap iron, and the oxide serves to precipitate 

 fine silt and plankton, and finally to form a filtering 

 coiiche on the sand beds (Fig. 3). It is here that the 

 sedimentation by tortuous movements, and by conducting 

 the flow over and under baffles, has been found to give 

 such admirable results. 



-Inoiher remarkable system which is doing good work 

 in the banlieue of Paris is the Puech-Chabal. Here the 

 raw water is first passed through the roughing filters, 

 dt-grossisscurs, so called, in which it leaves a large part 

 of the suspended matters. The degrossisseurs are com- 

 posed of grits and pebbles graded from about walnut size 

 to gravel in the last of the series. The rough filtration 

 enables the finishing filter to continue in operation for a 



cation have brought about many valuable improvements, 

 and it may be expiected that the future has much in store 

 for the water engineer. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Cambridge. — The following have been nominated to 

 serve, for eight years from February 20, on the board of 

 electors to the professorship mentioned before their 

 names : — Chemistry, Prof. Wood ; Pliimian, Mr. MoUi- 

 son : Anatomy, Dr. Langley ; Botany, Prof. I. B. Balfour; 

 Geology, Dr. A. S. Woodward ; Jaeksonian, Prof. 

 Larmor ; Medicine (Downing), Dr. Fletcher ; Mineralogy, 

 Dr. Marr ; Political Economy, Dr. Marshall ; Zoology and 

 Comparative Anatomy, Mr. F. Darwin ; Experimental 

 Physics, .Sir W. D. Niven ; Mechanism and Applied 

 Sciences, Dr. Forsvth ; Physiologv, Prof. Starling ; 

 Surgery, Dr. Gaskell i Pathology. Sir T. Clifford AUbutt : 

 and Agriculltire (.Drapers), Prof. Biffen. 



XO. 2050, VOL. 79] 



