SCIENTIFIC SUMMARY. 
329 
leased on assumptions which can at best be merely approximately correct. — 
( Chemical News , 1878, xxvii. 108.) 
In the current number of the Mineralogical Magazine , Prof. Heddle, of 
St. Andrews, draws | attention to two properties of Sonstadt’s “ solution ” 
which cannot too soon be impressed upon those who purpose to use it : it is 
a rapid and powerful vesicant, and it is exceedingly poisonous. It happened 
that some drops fell upon one of his hands, which was soon found to be in a 
state of violent inflammation. He does not regard the liquid as a 11 solution ” 
in the strictest sense, but believes that a new salt is formed, which crystal- 
lizes in long needles apparently belonging to the oblique prismatic system ; 
they have a highly dispersive power, a sulphur yellow colour, and are ex- 
tremely deliquescent. — ( The Mineralogical Magazine , 1878, ii. 63.) 
Fluid Cavities in Blende. — A. Schortel has remarked the occurrence of a 
cavity, of nearly the size of a pea, and filled with liquid, in a specimen of 
Spanish blende. When the specimen was broken through the liquid was 
ejected. The walls of the cavity and the cleavage-faces were washed 
with distilled water and the transparent liquid qualitatively examined. 
The solution appears to have contained sodium chloride and zinc sulphate, 
the former predominating {Berg, und Huttenm.-Zeitung , xxxvii. 49). Little 
•cubes of salt have not unfrequently been observed in fluid cavities of other 
minerals. 
A Societe de Mineralogie has been formed in Paris. M. des Cloiseaux 
is president, and the meetings are held on the second Tuesday of each month 
in the Mineralogical Laboratory of the Sorbonne. 
PHYSIOS. 
The Microphone. — It was announced early in May last that Professor 
Hughes, the inventor of the type-printing apparatus, had made the discovery 
that certain bodies placed in the circuit of a small battery were so affected 
by the sonorous vibrations of speech as to replace the transmitter of a Bell 
Telephone. 
The instrument producing such remarkable results was described at the 
meeting of the Royal Society on the 9th of that month. 
The telephone was employed as a phonoscope or receiving instrument of 
great delicacy, a small Daniel’s battery being introduced into its circuit. 
It was first noticed that if a stretched wire were made part of this circuit, 
and the strain increased until it broke, a sound was heard at the moment of 
breaking, and repeated if the broken ends were pressed together. 
“ It was soon found that it was not at all necessary to join two wires 
endwise together to reproduce sound, but that any portion of an elec- 
tric conductor would do so, even when fastened to a board or to a table ; 
no matter how complicated the structure upon this board, or the materials 
used as a conductor, provided one or more portions of the electrical con- 
ductor were separated, and only brought into contact by a slight but constant 
pressure. Thus, if the ends of the wire terminating in two common nails 
laid side by side, and separated from each other by a small space, be electri- 
cally connected by laying a similar nail between them, sound could be repro- 
