150 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ventilation ; and, 5th, petroleum, when burned in well-con- 

 structed lamps, gives rise to less carbon dioxide, and, what 

 is more important, to less imperfectly burned matter, than 

 any other illuminating agent. For equal light, stearin can- 

 dles render the air most impure, the proportion for petro- 

 leum, gas, oil, and candles being 1:4:4:7. An ordinary 

 room of a capacity of 100 cubic meters would contain, if 

 lighted with petroleum (the light being equal to six candles), 

 56 cubic centimeters of carbon dioxide and 1.7 of marsh iras : 

 it" lighted with gas, 47 and 6.9 cubic centimeters; with oil, 

 109 and 7.2 cubic centimeters; and with candles, 125 and 

 18.7 cubic centimeters; the cost of the petroleum for 24 

 hours being 5 cents, of the gas 13 cents, of the oil (rape oil) 

 15 cents, and of the candles 72 cents. 



Coquillion has proposed a new method for detecting and 

 estimating the amount of fire-damp in mines. As is well 

 known, the blue aureole which surrounds the flame of the 

 safety -lamp when in an explosive atmosphere is the only 

 means at present in use for ascertaining the presence of 

 fire-damp, but this requires at least 6 to 8 per cent, of marsh 

 gas to produce the effect. The new method is founded on 

 the fact, first observed by him, that hydrogen and hydro- 

 carbons generally are completely burned in presence of oxy- 

 gen, and without detonation, by means of a palladium wire 

 brought to a white heat. The carbon dioxide thus gener- 

 ated is afterwards estimated in a graduated tube. Two 

 pieces of apparatus have been made one for use in the 

 mine, which detects the carbon dioxide produced by the in- 

 candescent palladium, and thus shows the fire-damp; the 

 other for use above ground, in determining accurately the 

 amount present. 



Bischof has examined the action of spongy iron upon the 

 low forms of organic life which form the specific poison of 

 cholera, typhoid fever, etc. He finds that bacteria are ren- 

 dered permanently harmless when passing into water through 

 spongy iron. Even effluent sewage water, after passing 

 through the spongy iron, remained perfectly clear for five 

 years, though exposed to both light and air. The author 

 asserts that the action of this material consists largely in the 

 reduction of the ferric hydrate, the ferrous compound result- 

 ing being again oxidized by the oxygen in the water. 



