SCIENTIFIC SUMMARY. 
267 
chloroform — Mr. Simpson gave the preference to newly -made starch paste 
as being the most suitable on account of the rapidity with which the fresh 
paste may at any time be produced in a state fit for use, with such 
facility, indeed, that no inducement was offered for the employment of a 
sample which had become tainted and acid by long keeping. 
With reference to the applicability of certain kinds of stained glass for 
photographic use, the employment of the Spectroscope appears to have done 
good service in the selection of suitable varieties. Mr. Crookes has 
reported the experimental results obtained in the examination of a series 
of samples, whereby, in the case of orange glass, great differences were 
observed in regard to their power of intercepting the active photographic 
rays, which by the unassisted ocular inspection were quite inappreciable. 
Photography on Phosphorus. — Dr. Draper has recently published a curious 
process : he forms a thin sheet of phosphorus by melting it between two 
glasses ; this is exposed to the light, and is stated to become red. Dr. Draper 
appears to have produced on this phosphorus plate good impressions of the 
solar spectrum, with all the fixed lines very faithfully delineated. Some 
of these prints have been preserved for many years. 
This has been claimed as a new discovery ; but Bockman more than half 
a century since found that by exposing phosphorus in nitrogen to sunshine, 
there was deposited upon the side of the glasses, nearest the light, a red 
powder. He also discovered that a stick of phosphorus, exposed to the 
action of the solar spectrum, was bleached by the blue and violet rays, 
whilst it became red under the action of the red rays. 
PHYSICS. 
ACOUSTICS. 
Musical Notes . — Professor Zantedeschi has for some time been engaged in 
acoustic experiments. He has published no less than nine papers on the 
subject in the Sitzungsberichte, of Vienna. The principal object of the author 
has been the determination of a fixed note, to which, as to an invariable unit 
of measure, the notes of different instruments may be referred. He informs 
us that the number of vibrations per second which produce the note C is 
from 272 to 276 at St. Petersburg, 271 in Naples, 268 in Milan, 266 in 
Venice, and 268 in Viemia. Lissajous states that in Paris the number of 
vibrations of the note A was 898 in 1856 ; while Sauveur informs us that in 
1715 it was only 810. Professor Zantedeschi attributes this to a molecular 
change, gradually developed in the steel of which tuning-forks are made. In 
order to eliminate this source of error, he proposes to substitute for the 
tuning-fork a pipe such as is used at the present time by tuners of instru- 
ments in the south of Italy. He compared a number of tuning-forks and 
pitch-pipes known to be more than fifty years old, and found that the former 
had become higher, though unequally, when compared with the latter. In 
order to secure the fixity of a note, Zantedeschi considers that it should be 
