294 Dana on Waz. 
in a battery of the common form, two feet long, one foot wide, 
and ten inches high, and containing 18 coated jars, there will be 
no more than 3500 square inches of coated surface, while in a 
battery of the same dimensions on the proposed construction, 
- there will be no less than 8y00 square inches covered with tinfoil, 
allowing the sheet of glass and of foilto be } inch thick. 
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 re- 
main perfect. This form of the Electrical Battery is very por 
table; it 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. 
Ant: XV. Chemical Examination of the Berries of the Myrica 
~ Cerifera, or Wax Myrtle, by J. F. Dana, M. D. Chemical Assis- 
tant, in Harvard University, and Lecturer on Chemistry and 
Pharmacy in Dartmouth College. 
~ “\ «(Communicated for this Journal.) 
Tar myrtle wax of commerce has been examined by Dr. Bos- 
tock 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 jn re- 
peated portions of warm alcohol, until the fluid appeared to eX 
ert no further action. The first portions of alcohol were tinged 
of agreen color, but the last portions remained colorless. 
I]. The alcoholic solutions were poured into a small re 
known weight; the alcohol was carefully distilled off, and the 
residuum dried; deducting the weight of the retort, there re- 
mained 18.5 grs. for the weight of the matter dissolved by the 
alcohol. : 
tort of 
