614 Foreign and Miscellaneous Intelligence. 



containing water, sometimes raises that part of the hoiler to a dull 

 red heat, which suddenly coming in contact with a portion of the 

 contained water, generates steam with such rapidity as to burst the 

 boiler. In order to ascertain the effects of different metals, raised 

 to different temperatures, in generating steam from boiling water, a 

 series of experiments have been undertaken by Mr. Johnson, of 

 Philadelphia, which contain the following results. He found by 

 immersing iron raised to different temperatures in boiling water, that 

 more steam was generated in a given time by iron of a red heat, just 

 visible in day light, than by the same piece of iron raised to a white 

 heat. This may arise from the greater quantity of steam forming 

 an atmosphere around the white hot iron, and thus preventing the 

 water coming in contact with the iron. The steam generated bears 

 a direct relation to the weight of the metal, being about one pound 

 of steam for every nine pounds of iron. In comparing cast iron 

 with malleable, he found that cast iron raised to the same temperature 

 generates more than wrought iron, being about one pound of steam 

 for every eight pounds and a quarter of iron*. 



4. ON THE PREPARATION OF IODIC ACID. (Serullas.) 



In the course of experimental investigations, M. Serullas had made 

 out that iodic acid was insoluble in alcohol, and that the perchloride 

 of iodine acted upon, and was decomposed by, water. Upon these 

 two points he has founded a process for preparing pure iodic acid in 

 an economical manner. For this purpose the perchloride of iodine, 

 saturated to the utmost with chlorine, and in the solid state, must be 

 prepared, and a small quantity of water, or, what is better, a solution 

 of the perchloride put into the flask with it ; some fragments of glass, 

 for the purpose of detaching the solid chloride from the vessel, are 

 also to be added, and then this mixture of glass, fluid and solid chlo- 

 ride of iodine is to be transferred by a funnel into a stoppered 8 or 

 10-ounce phial, in which it may afterwards be strongly agitated the 

 funnel retains the fragments of glass, which may be washed with a 

 little saturated solution of perchloride. The bottle is then to be vio- 

 lently shaken to reduce the solid chloride to powder, that all parts 

 may come in contact with the liquid, and that it may be freed from 

 subchloride as much as possible. The whole is then to be poured 

 into a capsule, as much liquid as possible decanted, and then small 

 quantities of ether, or strong alcohol, added, agitating the whole with 

 a glass rod. Almost immediately the solid part becomes white, and 

 the liquid yellow : it is then to be decanted, and the washing repeated, 

 until the liquid comes off colourless. In this way the acid is ob- 

 tained as a white crystalline powder, perfectly pure, which, being 

 dried and pressed under the finger, feels like very fine sand ; or it 

 may be dissolved, filtered, and crystallized by mixture with sul- 

 phuric acid, as formerly described f. 



* Silliman's Journal, vol. xix. p. 292. f Quarterly Journal of Science, xxix. 411, 



