CHEMICAL SCIENCE. 243 



intensity current) on cast iron, while about to consolidate in the 

 mould, I found that the metal thus treated had acquired a much 

 closer grain, lighter color, and had become exceedingly strong when 

 compared with iron that had been poured at the same time into a 

 similar mould and from the same mass. The same effect I also pro- 

 duced on steel, when, immediately after casting and previous to its 

 consolidation, an interrupted and rapidly-reversed intensity current 

 of electricity was passed through the same. 



" The violent pulsations of intensitive electricity, the rapid changes 

 of polarity, prevented the growth of larger crystals ; they contracted, 

 and in some respect changed the molecular structure of the metal. 



"Another valuable feature attended the application to steel, name- 

 ly, that after breaking the bar of steel no honey-combs, as the air- 

 cavities that usually appear in cast steel are called, could be detected. 

 For large castings, for instance of ordnance, steam cylinders, etc., 

 the application of electricity may become of great importance; the 

 use of the magneto-electric machine, moreover, requiring nothing 

 but the adjustment of a belt, reduces the expense for the electric 

 force to a very small figure." 



OZONE PRODUCED BY PLANTS. 



M. Kosrnan has communicated to the French Academy a series 

 of observations, from which he draws the following conclusions: 



1. Plants evolve ozonized oxygen from their leaves and green parts. 



2. They disengage, during the day, ozonized oxygen in a greater 

 ponderable quantity than exists in the circumambient air. 3. Dur- 

 ing the night the difference between the ozone produced in the plants 

 and that contained in the air becomes nil in the case of isolated vege- 

 tation, but where the plants grow thickly and vigorously this ozone is 

 more abundant than that of the air. 4. Plants in the country evolve 

 more ozone during the day than town plants. 5. From this cause 

 country air is more exhilarating than town air. 6. In the midst of 

 towns, and of a dense population, the night air exhibits more ozone 

 than that of the day, but in proportion as the animal population 

 diminishes, and the vegetable kingdom predominates, the diurnal 

 ozone increases until it exceeds that of the night. 7. The interior of 

 the corollas of plants do not evolve ozone. 8. Inhabited rooms do 

 not usually contain ozonized oxygen. 



