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Monday, April 30, 1849. 

 Bishop TERROT, V.P., in the Chair. 

 The following communications were read : — 



1. On a New Voltaic Battery of Intense Power. By Dr 



"Wright. Communicated by Dr George Wilson. 



The author placed on the table a battery of four pairs, each con- 

 sisting of a rod of coke 2^ inches long by IJ in diameter, surrounded 

 by a cylinder of amalgamated zinc, 2\ inches high by 2\ inches in 

 diameter ; the different pairs were firmly attached to the same bar 

 of wood, and could be immersed in jars of stoneware at once. The 

 arrangement was charged with a mixture of nitric acid one part, 

 sulphuric acid four parts, water eight parts. The author stated that 

 he considered the power of the battery, which was twice that of 

 Grove's, was duo to the heat generated on the surface of the zinc by 

 the local action of the nitric acid. 



2. On a New Species of Manna, from New South Wales. 



By Thomas Anderson, M.D. 



About thirty years ago a species of manna, obtained from the 

 Eucalyptus Mannifera, was brought from New South Wales, and 

 was examined by Dr Thomas Thomson, and afterwards by Professor 

 Johnston, both of whom ascertained it to contain a new species of 

 sugar, different from the mannite which exists in ordinary manna. 

 The author had, through the kindness of Mr Sheriff Cay, an oppor- 

 tunity of examining a very different species of manna, remarkable 

 both from its chemical constitution, and from its possessing a defi- 

 nitely organised structure. This substance was discovered by Mr 

 Robert Cay in 1844, in the interior of Australia Felix, to the north 

 and north-west of Melbourne, where it occurs at certain seasons on 

 the leaves of the Mallee plant, Eucalyptus Dumosa, and is known to 

 the natives by the name of Lerp. 



It consists of numerous small conical cups of the average diameter 

 of a sixth of an inch, more or less distinctly striated, and covered 



