D. CHEMISTRY AND METALLURGY. 209 



is richer in ozone than in summer, and that therefore forests, 

 as such, evidently do not exert any influence through their 

 leaves, but possibly through their greater moistness. Zittel, 

 however, thinks there is no relation between vegetation and 

 atmospheric ozone. Zeitschrift fur Meteorologie, IX., 312. 



THE PHYSICAL PROPERTIES OF HYDROGENIUM. 



The interesting substance known to chemists as hydroge- 

 nium has been the subject of some physical measurements 

 by Dewar, who has attempted to make a new determination 

 of its specific heat and its co-efficient of expansion. The only 

 condition under which hydrogenium is known to exist is that 

 of an alloy with the rarer metals, palladium, platinum, etc. 

 As the result of his experiments with palladium and hydro- 

 gen, the specific heat of hydrogenium is concluded to be al- 

 most exactly 3.4. The co-efficient of cubical expansion ap- 

 pears to be very nearly 0.00025. 



THE COMBUSTIBILITY OF IRON. 



The following elegant lecture experiment for illustrating 

 the combustibility of iron was originated by the late Pro- 

 fessor Magnus, of Berlin. A mass of iron filings is approach- 

 ed by a magnet of considerable power, and a quantity there- 

 of permitted to adhere to it. This loose, spongy tuft of iron 

 dust contains a considerable quantity of air imprisoned be- 

 tween its particles, and is therefore, and because of its com- 

 minuted condition, well adapted to manifest its combustibil- 

 ity. The flame of an ordinary spirit-lamp or gas-burner 

 readily sets fire to the finely divided iron, which continues 

 to burn brilliantly and freely. By waving the magnet to 

 and fro, the showers of sparks sent off produce a striking 

 and brilliant effect. 



NEW METHOD FOR ASSAYING IRON. 



W. N. Hartley recommends a new and beautifully simple 

 method of assaying iron ores, in which the only apparatus 

 needed is a balance without weights, and a burette. To 

 begin with, a quantity of pure iron wire is taken (about 

 five grammes), and balanced by a sample of the pulverized 

 ore. The ore and wire are then separately dissolved, and 

 each solution titrated in the usual manner by permanganate 



