Proceedings of the Polytechnic Association. 799 



Piers in Sea Water. 

 The timber piles forming the foundation of the railway bridge at 

 Providence, R. L, having been almost eaten through above the sea 

 bottom by worms, Mr. Gushing, the resident railway engineer, caused 

 wooden piles to be driven, in groups, down through forty feet of mud 

 to the hard pan, and inclosed the top of each group with a cast iron 

 cylinder, which extends downward a little below the sea bottom, so 

 as to prevent any contact of wood and water, thus effectually exclu- 

 ding the teredo, and forming a foundation of the most permanent 

 character. 



ITew Pluorescent Solution. 



M. Ditte, of Paris, has obtained from Cuba wood (Morus tinctoria), 

 a solution possessing remarkable fluorescent properties. His process 

 in preparing the solution is to dissolve the cake in an excess of acetic 

 acid which is accomplished in the course of twenty-four hours. Six 

 times its volume of alcohol is then added and the mass filtered. The 

 resulting liquid is red by transmitted light, and by reflected light a 

 magnificent green. If pure ether is added to the acetic acid solution, 

 a yellow matter is precipitated, and the liquid loses its dichroic pro- 

 perty, while the precipitate dissolved in alcohol retains it. A decoc- 

 tion of Cuba wood is not dichroic, but becomes so by the addition of 

 acetate of alumina. The fluorescence is very vivid with the magne- 

 sium light and in Geissler tubes, but is not visible in the light from a 

 lamp, candle, or gas burner. 



The Abyssinian Jibara. 



A recent number of The Journal of Travel contains an illustration 

 of this singular plant, which has no branches, and puts fortli leaves 

 only around the middle of the trunk, the upper portion being entirely 

 bare. The Journal says : " There are a number of forms peculiar to 

 Abyssinia itself, the most remarkable of which,' perhaps, is the won- 

 derful Jibara {Rhyncho-petalum Tnontanmn), the zone of which begins 

 at 11,000 feet, and continues, so far as the soil extends, up to the 

 highest tops, at first mixed with Erica and Hypericum, then standing 

 in thousands on the short grass, of the meadows, blooming among 

 numerous small alpine plants. It has long been known as one of the 

 most striking plants of the country. Jussieu and most botanists have 

 ranked it among Lobeliacese, but we think Robert Brown formed a 

 truer estimate of its afiinities when he placed it in the neighboring 



