240 Proceedings of the British Association. 



incandescent state, the necessary hardening will not take place on 

 plunging it into water. It is, therefore, necessary that a certain 

 temperature 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. In a great many 

 cases, the explosions have occurred during the cooling of the boilers 

 after the withdrawal of the fire. An experiment was shown in proof 

 of the view entertained by M. Boutigny. A sphere of copper, fitted 

 with a safety-valve, was heated, and a little water being put into it, it 

 was securely corked up, and withdrawn from the lamp. As long as 

 the metal remained red, everything was quiet ; but upon cooling, the 

 cork was blown out with explosive violence. The concluding ex- 

 periment excited great interest. The production of ice in a vessel at 

 a glowing red heat was a result so anomalous, that every one was 

 desirous of witnessing the phenomenon for himself. It was beautifully 

 performed by M. Boutigny, in the following manner : — A deep platina 

 capsule was brought to a glowing red heat, and at the same moment, 

 liquid sulphureous acid, which had been preserved in the liquid state 

 by a freezing mixture, and some water, were poured into the vessel. 

 The rapid evaporation of the volatile sulphureous acid, which enters 

 into ebullition at the freezing point, produced such an intense degree 

 of cold, that a large lump of ice was immediately formed, and being 

 thrown out of the red-hot vessel, handed round to the company 

 in the Section. 



Mr. G. Rennie referred to some experiments of his own, in con- 

 firmation of M. Boutigny' s views. 



Friday. 

 Section C— GEOLOGY AND PHYSICAL GEOGRAPHY. 

 * Report on the Microscopic Structure of Shells,' by W. B. 

 Carpenter, M.D. — This report formed the continuation of last year's 

 [Journ. Nat. History, p. 442], on the minute structure of the skele- 

 tons of Bivalves and Echinodermata. Dr. Carpenter stated that he had 



