ON THE SILENT DISCHARGE OF ELECTRICITT. 43 



imable to report more fully on this point and on the main object of their 

 work, viz., the influence of heat, pressure, &o., on the formation 

 of ozone. Further pro,2:ress has been made in the examination of the 

 character of the silent discharge of electricity, and in the study of the 

 actions of ozone and mercury on each other. It has been ascertained 

 that ozone, pure and dry, except for the presence of oxygen, afi'ects the 

 surface-tension of mercury in the well-known manner, and is itself presently 

 reconverted into oxygen. This change, however, is not accompanied by 

 oxidation of the mercury, such as occurs even when only a trace of 

 moisture is present. 



The experiments on the chemical action of ozone on mercury and 

 other substances are being continued, and, though their progress must be 

 slow, considerable advance may be hoped for during the coming year. 

 The other work undertaken by the Committee is also being actively con. 

 tinned, and it is proposed that the Committee shall be reappointed. 



Note. — No experimental details are introduced into this report, as 

 a full description of the work done has already been published in a paper 

 printed in the ' Journal of the Chemical Society ' for July 1887. 



Report of the Coowmittee, consisting of Professors Tilden and W. 

 Chandler Eoberts-Austen and Mr. T. Turner (Secretary), 

 appointed for the purpose of investigating the Influence of 

 Silicon on the Properties of Steel. (Di^awn up by Mr. T. Turner.) 



When the above Committee were appointed at the last meeting of the 

 Association a series of experiments had already been commenced, and a 

 preliminary notice of these appeared in the Report for last year. This 

 series of experiments has been completed, and full details have been 

 published ('Jour. Chem. Soc' 1887, p. 129). A second set of observations 

 in continuation of the work has also been commenced, and the results are 

 so far advanced that it is hoped to publish details in a few months. 



In the paper in the ' Journal of the Chemical Society ' a short account 

 is given of the results hitherto obtained by other observers, and it is 

 believed that the present state of our knowledge may be summarised as 

 follows : — 



1. Ingot iron. Silicon promotes soundness; it resembles carbon in 

 increasing the tenacity and hardness ; it should not exceed 0'15 per cent, 

 if the metal has to be rolled ; and in some cases it produces brittleness 

 when cold. 



2. In steel castings. Silicon promotes soundness ; it is, however, re- 

 garded as a necessary evil, and excess should be avoided as tending to 

 brittleness and low extension ; about 0'3 per cent, is generally recom- 

 mended. 



3. In crucible steel. A few hundredths per cent, is necessary to pro- 

 duce soundness ; it is generally agreed that considei'able quantities of 

 silicon may be present without injury to the material. 



4. Manganese appears to be capable of neutralising the ill effect due 

 to silicon. 



The first series of experiments was undertaken to determine the 

 effect of silicon on the properties of specially pure iron. For this purpose 



