FOREIGN EXTRACTS. 317 



tion ; but as it slowly cooled, boiling took place. The application of 

 these principles, involved in these phenomena that which appears 

 in the tempering of steel. If a metal to be tempered is in a liighly 

 incandescent state, the necessary hardening will not take place on 

 plunging into water. It is therefore necessary that a certain tempera- 

 ture should be observed. Experiments were made to show that the 

 repulsive power of the spheroidal fluid existed not merely between 

 it and the hot plate, but between it and other fluids. Ether and 

 water thus repelled each other, and water rested on and rolled over 

 turpentine. 



The bursting of steam boilers came next under consideration, 

 and it was shown that many serious explosions may be referred to 

 the phenomena under consideration, ]n a great many cases ex- 

 plosions have occurred during the cooling of the boilers, after the 

 fire was withdrawn. An experimcni was shown in proof of the view 

 of the Professor. A sphere of copper, fitted with a safety valve, 

 was healed, and a litlle water put into it : it was securely corked, and 

 withdrawn from the lamp. .As long as the metal remained red, every 

 thing was quiet ; but on coolmg, the cork was blown out with 

 violence. 



The concluding experiment excited great interest. The production 

 of ice, in a vessel at a red heat, was so anomalous, that every one 

 was desirous of witnessing the phenomenon. It was performed in 

 the following manner : A deep platina capsule was brought to a 

 glowing red heat, and at the same moment liquid sulphurous acid 

 and some water were projected into the vessel ; the rapid evapora- 

 tion of the volatile sulphurous acid, which enters into ebullition at 

 the freezing point, produced such a degree of cold, that a large 

 lump of ice was immediately formed, and being thrown out of the 

 red hot vessel, was handed round to the company. 



On the chemical changes occurring in iron furnaces. By Dr. Lyon 

 Playfair and Prof, Bunsen, 

 The object of the paper was to determine the gaseous products 

 of hot-blast iron furnaces. It was found that the process of coking 

 continued down in the furnace to the depth of 24 feet, but the dis- 

 tillation reached its maximum at the depth of 14 feet, and that the 

 formation of tar took place at between 14 and 17 feet. A great dimi- 

 nution of oxygen is found to occur at those points where the gases 

 become developed, and hence they pass away unconsumed or without 

 undergoing combustion. It has been estimated that 91 per cent of 

 the heating material is thus lost in the form of gaseous products. 

 The authors suggest as a means of remedying these losses, to con- 

 struct a canal just at the point where the gases are given off, for 

 the purpose of conveying these products to other parts where their 

 high heating and illuminating powers may be employed advanta- 



