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SCIENTIFIC NEV\^S. 



[May 25, 1888. 



Mr. Thomas Turner detailed the nature of some ex- 

 periments he had made as to the condition of silicon in 

 cast-iron, from which he deduced that silicon has the 

 power of expeUing sulphur. The conclusions derived 

 from this portion of the subject may be briefly summarised 

 as follows : — Under certain conditions compounds may be 

 obtained from cast-iron which contain very considerable 

 quantities of both sulphur and silicon. Such compounds, 

 however, are unstable, tending to decompose on melting. 

 The silicon with the greater part of the iron remains, 

 while most of the sulphur is eliminated. Part of the 

 sulphur passes away in the gaseous form, but much of it 

 is found either in the condition of graphite matter rich in 

 sulphur or sulphur balls. In the presence of a slag much 

 of the ehminated sulphur is met with in the form of 

 sulphide. It appears probable that with a certain per- 

 centage of silicon there is a definite amount of sulphur 

 which cannot be exceeded under given furnace condi- 

 tions. The general conclusions arrived at after an 

 investigation of silicon and sulphur in the blast furnace 

 were that in the blast furnace there are three chief agencies 

 at work tending to eliminate sulphur, of which in Cleve- 

 -land ■ practice not more than one-twentieth passes into 

 the iron- (i) a high temperature tends to prevent 

 the absorption of sulphur by iron; (2) a slag rich 

 in lime readily combines with sulphur ; (3) the 

 amount of sulphur actually retained by the metal is in- 

 fluenced by the proportion of silicon, and probably also 

 of other elements in the iron. For every proportion of 

 silicon there is, with given furnace conditions, a corre- 

 sponding maximum proportion of sulphur. In the blast 

 furnace under normal conditions this maximum is not 

 exceeded, and is very seldom reached. If by any means 

 an excessive amount of sulphur be present, smelting eli- 

 minates sulphur and tends to produce a condition of 

 equilibrium. 



M. F. Gautier, of Paris, in a paper on " The Melting 

 in Cupola Furnaces of Wrought Iron or Steel Scrap 

 Mixed with Ferro-Silicon," remarked that the introduc- 

 tion of ferro-silicon, which has been watched with a good 

 deal of interest in metallurgical circles, has provided us 

 with a new alloy that has the power of converting a 

 white pig into a grey one, and which is well adapted for 

 the majority of foundry uses. The chief disadvantage 

 appears to be that of cost. Experiments which the 

 reader of the paper had made, demonstrated that ordinary 

 wrought iron scrap, and especially of the smallest kind, 

 which can be had at a very low price, yields probably as 

 good results as castings made with ordinary steel scrap. 

 In this case grey metal is obtained of a close grain and 

 very sound castings, which are homogeneous and abso- 

 lutely without blow-holes, and if we consider that the 

 resistance of the metal to shock is usually double that 

 which is obtained with ordinary good cast-iron, it appears 

 that there is a special market for such castings, which 

 might, at a comparatively low price, be substituted for 

 the steel castings generally employed. 



Mr. James Johnston gave an interesting account of the 

 system of industrial partnership that has been carried 

 into effect at the works of M. Godin, at Guise, in France', 

 and also the plan of housing those who are employed in 

 the foundry. The reader of the paper then proceeded to 

 describe the moulding machinery and other appliances 

 used at the works of Guise for the making of cast-iron 

 ranges for cooking and other domestic purposes. The 

 d'scussion of the paper was adjourned until the autumn 

 meeting. 



Major L. Cubillo, in the course of a paper on "Steel 

 Castings for the Manufacture of Guns," described the ex- 

 periments which he had pursued, with the view of 

 ascertaining whether, owing to the high prices of steel 

 forgings for the manufacture of guns, it would not be 

 possible to produce trustworthy artillery from steel 

 castings. The conclusion he arrived at was that, while 

 the possibility of manufacturing great flawless steel cast- 

 ings might not be completely established, and while a 

 casting by tempering at different temperatures might be 

 capable of acquiring the characteristics of steel forged and 

 tempered, yet the latter method must be used in the con- 

 struction of guns. 



Captain L. Cubillo, in a paper on "The Manufacture and 

 Treatment of Steel for Field Guns," described the manu- 

 facture and treatment of steel for field guns as practised 

 at Trubia. 



SOCIETY OF ENGINEERS. 

 At a meeting of the Society of Engineers, held at West- 

 minster Town Hall, on Monday evening. May 7th, Mr. 

 A. T. Walmisley, President, in the chair, a paper was 

 read on " Filtration by Machinery " by Edward Perrett, 

 A.M.Inst. C.E. 



The paper first compared the processes of straining 

 and filtering, and pointed out that in the latter process 

 the mutual attraction of particles of matter, in addition 

 to the straining action, causes the retention of the sus- 

 pended material in a liquid passing through the filtering 

 medium. After describing the early experiments made 

 by the author in filtering Thames water through filter 

 bags such as are used for the filtration of sugar, the 

 paper pointed out the danger of using animal charcoal 

 for the filtration of drinking water. This material has 

 the power of taking out matter in an infinitely fine state 

 of division and even in solution, the charcoal becoming 

 so charged with such matter that nothing short of subject- 

 ing the charcoal to a red heat is sufficient to thoroughly 

 clean it. An animal charcoal filter with any system of 

 washing will gradually accumulate the very fine matter, 

 which may germinate, and at length be carried through 

 with the filtered water. A filter with a granular medium 

 (such as crushed retort coke), designed by the author, is 

 effectually cleaned by an upward stream of compressed 

 air occasionally applied ; this causes an agitation of the 

 material and the attrition loosens the dirt, which a small 

 current of water washes away. At a waterworks in 

 South America where these filters are used, 20,000 

 gallons of river water are filtered per hour, the floor 

 space covered being 37 ft. by 7 ft. 6 in., or an average 

 rate of nearly 100 gallons per square foot of filtering sur- 

 face per hour. 



The purification of water containing organic matter by 

 contact with iron was mentioned. The original method 

 of using Professor Bischoft"'s " spongy iron " on a large 

 scale was to mix the spongy iron with gravel, and to 

 use this mixture as a filter bed, but it was found that 

 the top surface became hard and impervious after a short 

 time, and Mr. Wm. Anderson introduced a machine to 

 supersede these spongy iron filter beds. His " Revolving 

 Purifier " causes ordinary iron borings to be mixed with 

 the water as it passes through the machine ; the water is 

 afterwards filtered through ordinary sand beds 



For the filtration of very muddy water for manufac- 

 turing purposes, sponge is used by the author. The 

 machine consists of a cylindrical casing, in which sponge 

 is compressed between two diaphragms ; the lower 



