746 REPORT— 1889. 



as fast as tliey present themselves, all harmful organisms being 

 destroyed. 



(b) The production of disinfectants for household purposes, 



(c) The application of the electric current to plates of oxidisable and non- 



oxidisable material, fixed in such manner that sewage passing between 

 them not only receives a precipitating agent, but the putrifying organic 

 matter in solution is oxidised to any extent that may be required, the 

 action being produced by metallic oxycblorides, nascent oxygen and 

 chlorine, thus combining in one process the results obtained by both 

 precipitation and irrigation, the intensity of the current not of necessity 

 exceeding two volts, the action entirely depending on the quantity of 

 the current employed. The oxidisable plates are by preference (for 

 various reasons) of iron. It is contended that the process follows 

 more nearly natural action than any other hitherto suggested. 



' TUESDAY, SEPTEMBER 17. 



Sub-Section I. 

 The following Papers were read : — 

 1. Blast Furnace Practice.^ By Sir Lowthian Bell, Bart., F.B.S. 



2. Chemin defer glissant.^ By Sir Douglas Galton, K.O.B., F.B.S. 



3. The Strength of Alloys at diferent Temijeratures. 

 By Professor W. C. Unwin, F.B.S. 



The strength of the commonly used alloys, such as gun-metal and brass, at 

 moderately high temperatures, is a question of some practical importance. It is 

 well known that iron and copper decrease in tenacity as the temperature is raised, 

 the latter in a very marked degree. There are also experiments showing a still 

 more considerable decrease of tenacity in gun-metal. The author's attention was 

 directed to the matter in studying some experiments made for the Admiralty in 

 1877. In these experiments copper, Muntz metal, and phosphor-bronze showed a 

 tolerably regular decrease of tenacity as the temperature was raised to 500° F. 

 But in the case of gun-metal the results were more anomalous. The gun-metals 

 tried were all alloys of copper, tin, and zinc. In the bars tried the tenacity 

 diminished tolerably regularly up to a temperature of 300° or 350°. But beyond 

 that temperature there was a sudden decrease of tenacity generally of more than 50 

 per cent., and at a temperature of 500° in several cases the tenacity had become 

 nil. Now at the high pressures, and correspondingly high temperatures, at which 

 steam-engines are often worked, gun-metal is exposed in many cases to tempera- 

 tures of 350° or 400°. It is practically important to know if at such temperatures 

 its strength is seriously impaired. At any rate, the author found that there were 

 but few experiments on the strength of alloys at different temperatures, and of 

 some of these the trustworthiness was doubtful. Hence it appeared that it might 

 be useful to make some new experiments. 



In the present experiments the bars to be tested were fixed in an oil-bath 

 heated by a gas-jet. The middle part of the bar for a length of two inches was 

 turned down to a diameter of 5 inch or ^a inch. The temperatures were taken by 



' This paper was mainly a reiJetition of the author's address as President of Section 

 B. See also Engineering, vol. xlviii. p. 359. 



2 Published in the Newcastle Daily Chronicle, September 18, 1889. 



