358 Prof. Draper on the Allotropism of Chlorine 
This form of experiment may be supposed imperfect, since 
the chlorine is in a moist condition and confined by water. I 
have therefore made the following variation. 
I took a tube A, (Fig. 4,) six inches long and half an inch in 
diameter, closed at one end and open at the other, and cemented 
its open end on a piece of flat plate glass M, N, one inch wide 
and two long, ground on both sides, and having a hole p one 
sixth of an inch in diameter perforated through it. 'This hole 
was not in the centre of the glass, but on one side, as shown in 
the figure. The interior of the tube was perfectly clean and dry. 
A second tube B, consisting, as shown in Fig. 4, of two por- 
tions; a wide portion B, and a narrower tube c, was cemented 
on another piece of ground plate glass, similar to the foregoing 
in all respects. The tube c was open at its lower, extremity ; 
and the entire capacity of Band ¢ conjointly was adjusted so as 
to be equal to the capacity of A. 
Next I filled A with dry chlorine, and Be with dry hydrogen ; 
and kept them from mixing until the proper time, by operating 
in the following way: I placed the ground glasses face to face, 
as shown in Fig. 5, with a small quantity of soft tallow between 
them, arranging them in such a way that the aperture which led 
to the interior of A was open. 
Through this aperture dry chlorine was conveyed. It was 
generated by a mixture of peroxide of manganese and chlorohy- 
dric acid in the flask D, (Fig. 6,) and passed along a tube H, fill- 
ed with chloride of calcium. A slender glass tube f, conveyed 
it to the bottom of A, which was then filled by displacing the 
atmospheric air. When A was supposed to be full of chlorine 
it was slowly lowered so as to bring the tube out of the aperture, 
and as soon as it was disengaged the glass plates were moved in 
such a manner by sliding them on one another, that the aperture 
leading into A was shut; but that leading into B was open. 
The vessel A was thus filled with dry chlorine and securely 
closed. 
In the next place I filled B with dry hydrogen, which was 
done as follows. Toa bottle G, (Fig. 7,) containing dilute sul- 
phuric acid and zinc, a drying tube K, of chloride of calcium 
was adjusted, and at its upper endacork fA, arranged so as to 
receive tightly the tube c. In a short time, therefore, B became 
full of dry hydrogen, the surplus escaping through the open aper- 
