Intelligence and Miscellaneous Articles. 559 



'o 



lbs. produced a permanent set of an inch square bar. The President 

 remarked that the calculation as to elastic forces was scarcely to be 

 confided in. Mr. Fairbairne in answer to another question, stated that 

 the hot blast iron was the more flexible and better capable of bearing 

 impact ; but that all the results of impact had been taken from calcu- 

 lations founded on cold blast iron. Mr. Fairbairne stated that the cry- 

 stalline appearance was finer in hot than in cold blast. There were 

 no experiments made on the loss by remelting, and none on wrought 

 iron, — all on cast iron. In reply to Mr. Cottam, he mentioned that 

 all the Scotch irons had no cinder j the composition of the others they 

 did not know. Great difficulty had been experienced on this point, 

 because the different manufacturers were unwilling to give information. 

 — Mr. Guest professed on his part the fullest readiness. — Some con- 

 versation took place with regard to the peculiarity of appearance in 

 the broken bars. The President remarked, that when a rectangular 

 bar of any substance is exposed either to fracture, or even to temporary 

 deflexion, a similar appearance was found : this was known from the ex- 

 periments on glass by polarized light. Mr. Fairbairne in assent, said the 

 crystals were always more compact in the edge than the centre. Mr. 

 Webster inquired whether the elastic weight was always less than one- 

 third of the breaking weight. Mr. Fairbairne said, always — and after- 

 wards replied to a question from Mr. Guest, that the Scotch hot blast 

 iron showed agreater comparative strength as compared with cold blast, 

 but that they had made no experiments on South Welsh iron. There 

 was a perceptible permanent set from 280 lbs,, the experiments being 

 of from five to ten minutes in duration, and it being possible to judge 

 the deflection to the 1000th part of an inch. — Mr. Webster said it had 

 been found that the first set was owing to the breaking of the first crust} 

 and that beyond the first permanent set up to the elastic limit, the de- 

 flexion increases exactly as the weight. Some further conversation 

 ensued, in which Mr. Smith and others took part, when Mr. Guest sug- 

 gested the propriety of further continuing these researches, to which 

 the President agreed, and suggested a recommendation to that effect 

 from the committee of the section to the General Committee. Athe- 

 naum, No. 516. 



LXXXI. Intelligence and Miscellaneous Articles. 



GASEOUS DIFFUSION. 



THE following experimenthas recently been made in the laboratory 

 of Prof. Draper, of Hampden Sidney College, Virginia, and com- 

 municated to us by him $ it is a good illustration of the endosmosis of 

 gases, and is well adapted for a class-room experiment. 



Take a two-ounce phial with a wide mouth, and having made a solu- 

 tion of soap in water of the consistency of a viscid lather, dip one of 

 the fingers into it, and pass it over the mouth of the phial j this will 

 leave a thin plane film stretched across it. Place over the phial thus 

 arranged a jar of protoxide of nitrogen, in the course of a few seconds 

 the horizontally of the film will be disturbed j it will become convex, 

 and at the end of a minute and a half or two minutes, it will form 



