Polytechnic Association Proceedings. 737 



ance, the opposite arm being counterpoised. In about a half an 

 hour the position of the balance will show that the Qgg has increased 

 in weight, in consequence of the passage of water through the mem- 

 brane. On substituting alcohol for the water surrounding this Qgg, 

 and adding weight sufficient to bring the arms to the same level, 

 after a short time the egg will begin to rise, thus proving that it 

 has become lighter in consequence of the passage of the water from 

 the eofo; into the alcohol. 



A NEW REAGENT. 



Prof, Bottger has prepared a new and highly sensitive chemical 

 test for acids and alkalis, fi*om the leaves of an ornamental plant 

 named, in honor of the Dutch horticulturist Verschaffelt, Ooleus 

 Verschaffelti. The reagent is prepared by digesting the fully 

 developed leaves in alcohol, and impregnating slips of Swedish 

 filter-paper with the decoction. This test-paper differs from litmus 

 — prepared from a certain species of lichen — in having a beautiful 

 red tint, which becomes green under the influence of an alkali or 

 alkaline earth. It is not affected by free carbonic acid (garet), so 

 that it may be used in detecting traces of carbonate of lime {calc- 

 masot) in water. A strip of this paper moistened in water and 

 held over a burner from which gas is issuing, assumes in a very 

 short time a green tinge, in consequence of the ammonia, from 

 which, perhaps, no gas is altogether free. 



LUMINOSITY OF PHOSPHORUS. 



Dr. Moffat described before the British Association, severaA 



interesting experiments he had made. Phosphorus in a luminous; 



state produces phosphorous and phosphoric acids, also ozone. 



Phosphorus is non-luminous below the temperature of 39'^ F., and 



is luminous above 45*^ F., but the point of luminosity varies with 



the pressure of the atmosphere and with the direction of the wind. 



Experiments extending over a period of four years had proved that 



the equatorial or searwind produces phosphoresence and ozone; 



and that the polar or land-wind has no such effect. As the ocean 



is the great resorvoir of ozone. Dr. Moffat concludes that the latter 



is developed by the phosphorescence of the ocean, and that were 



it not for the modifying influence of the polar winds, ozone at sea 



would be a constant quantity. 



/ 



ANEMOMETER. 



Mr. A. E. Fletcher exhibited at the British Association his instru- 

 ment for measuring the speed of air in flues and chimneys. It is 

 •^Inst,] 47 



