Chemistry and Physics. 67 
SCIENTIFIC INTELLIGENCE. 
I. CHEMISTRY AND PHYSICS. 
1. On a new Universal chemical Spectroscope-—A new form 
of spectroscope has been devised by G. Kriss, which is well 
adapted for the work of the chemical laboratory, both qualitative 
and quantitative.* Its fundamental form is that of the Bunsen 
and Kirchhoff instrument; but a variety of modifications and 
additions have been made, to render it available as a universal 
spectroscope. An upright pillar supports a table on which rests 
the prism, and which carries the observing, collimating and scale- 
telescopes. The collimating telescope has no draw-tube. It is 
provided with two slit-plates, one of which carries the ordinary 
single slit for qualitative purposes, the other the double slit of 
Vierordt for quantitative work. ‘These slits are strictly parallel 
to the axis of the prism and are opened and closed symmetrically 
on the two sides of this axis, by micrometer screws, whereby the 
width of the slit may be determined. The knife edges of these 
slits are made of platinum and are so accurately worked that no 
horizontal lines appear in the spectrum even when the slit is open 
by only one or two divisions of the micrometer-head (0°002 to 
0:004™™".) Two prisms are provided ; one a simple flint prism of 
60° of a dispersion of 4°18’ between A and H,, the other a so- 
called Rutherfurd prism, having a dispersion of 8° 2’ between the 
same limits. By an automatic device the prism is kept at the 
angle of minimum deviation for the part of the spectrum under 
observation. The scale is fixed in its telescope so that it is in the 
principal focus of the object glass and so that its 100th division 
comes midwayebetween the D lines. The observing telescope 
magnifies about seven diameters. By means of a micrometer 
screw with a divided head, it is moved in a horizontal plane about 
the vertical axis of the instrument, the amount of motion being 
measured by an index moving over a graduated arc upon the end 
of the fixed arm carrying the telescope. The value of the divis- 
ions on the micrometer head in terms of the graduations upon the 
arc, and the value of these in terms of the scale divisions, are 
easily determined. Moreover, this telescope has a micrometer 
eyepiece; so that spectrum measurements may be made between 
two colors whose wave-lengths differ by only 0:000 000 000 015 
millimeter. The slide which carries the cross wires of this 
micrometer carries also the Vierordt slit, whose width is adjusta- 
ble by the same screw that moves these cross wires. The author 
thinks that the results obtained by this instrument when used as 
a spectrophotometer, are fully equal to those obtainable with 
polarizing instruments.— Ber. Berl. Chem. Gres., xix, 2739-2745, 
November, 1885. G. F. B, 
* Constructed by A. Kriiss of Hamburg. 
