378 Plate Electrical Machines, = 
' 
Upon examining the tube with a lens, nothing was seen 
which could prevent the entrance of the alcohol 3 on with-— 
drawing the tube from ~ alcohol, the external! air Eater de 
with a hissing. E06 aie 
M. Doberéiner conceives that “ aisitietey of the sities 
was so small that the alechol could not enter, pus viel pe 
air which it contained. 
15. Leghorn Straw Plait: _—The Dublin Sodieen, hand 
offered premiums for the best imitations of Leghoro 
Plait, awarded three prizes to successful candidates. Not 
less than twenty-four specimens were exhibited fromwide= 
ly remote parts of Ireland. The finest specimen was made 
from Avena flavescens, or yellow grass, by Miss Corus of 
Plattin, near Drogheda. The second was made of Cynos- 
urus cristatus, or crested dog’s-tail grass, by Miss Grim- 
LryY, of Kiltenon, near Newton, Mount Kennedy. The third 
of Agrostis vulgaris, or common bent grass, by Miss Cane” 
BELL, of Londonderry. 
16. Difference of crystalline forms of the ev sub- 
stance.-—M. Mitscherlich, who first observed the remarkable 
fact that a body may affect two different crystalline forms, 
has, ina memoir on this subject, quoted sulphur as an in- 
stance. Natural crystals of sulphur are furnished by sone 
calcareous strata, and by volcanoes. Artificial crystals 
may be obtained either by evaporating a solution of it in 
carburet of sulphur, o1 by fusiun of the sulphur and slow 
cooling. On fusing native sulphur it gives the same crys- 
tals as common sulphur. The primitive form of the crys- 
tals of sulphur, either natural, or obtained as above by 
evaporation, is an octaedron, with a rhombic base; but 
the primitive form of the crystals obtained by fusion is 
an oblique prism, with a rhombic base. 
17. Plate electrical machines.—A variation in the con- 
struction of the plate electrical machine has been devised 
and practised by M. Metzger of Siblingen in Schaff house, 
which would seem to be a real improvement. Consider- 
ing that the effect desired in using the machine, was first 
highly to excite the glass, and then to collect the electri- 
city fromit, M. Metzger concluded that the distance be- 
