When plate glass is employed for making this battery, the ring of glass exterior to the tinfoil may be covered with varnish, and then the next plate laid over it; the tinfoil will then be shut out for ever from the access of moisture, and the insulation will remain perfect. This form of the Electrical Battery is very portable, may be packed in a case with the machine, and indeed a powerful battery occupies no greater space than a quarto volume. It is cheap and easily constructed. ART. XV. _Chemical Examination of the Berries of the Myrica Cerifera, or Wax Myrtle, by_ J. F. DANA, M. D. _Chemical Assistant in Harvard University, and Lecturer on Chemistry and Pharmacy in Dartmouth College_. (Communicated for this Journal.) The myrtle wax of commerce has been examined by Dr. Bostock and by M. Cadet; the entire berry not having been made the subject of analysis, I have been induced to examine it, with a view to ascertain the proportion of wax. I. Fifty grains of the most perfect berries were digested in repeated portions of warm alcohol, until the fluid appeared to exert no further action. The first portions of alcohol were tinged of a green colour, but the last portions remained colourless. II. The alcoholic solutions were poured into a small retort of known weight; the alcohol was carefully distilled off, and the residuum dried; deducting the weight of the retort, there remained 18.5 grs. for the weight of the matter dissolved by the alcohol. III. The substances which had been dissolved by the alcohol consisted of two portions, viz. the wax, which was of an apple-green colour, and a reddish brown substance; this substance was supposed to be resinous, and the contents of the retort were therefore digested in acetic acid; the acid soon became of a reddish brown colour, and dissolved nearly the whole of the matter in the retort, leaving the wax. The acid solution, together with a small portion of insoluble reddish matter, were carefully separated from the wax. The wax being dried and melted, weighed 16 grains. IV. The acetic acid solution was evaporated to dryness, and a dark brown matter was obtained; it was almost totally soluble in warm alcohol, from which it was precipitated by water; it was supposed therefore to consist chiefly of resin, with a small portion of extractive matter, and may be called resino-extractive; it weighed 2.5 grains. V. The matter insoluble in alcohol consisted of two parts, viz. the kernels and a fine-grained black powder, having very much the appearance of fine gunpowder; the powder was carefully separated from the kernels by a wire sieve, and weighed 7.5 grains. The kernels were found to weigh 23.75 grains. From this analysis it appears that the entire berries consist of