CHEMISTRY. 29 
passed, its bulb supported by the ring, c,c. Into this matrass the 
substance is introduced, which is to be dried at any temperature. The 
opening of the matrass must be closed by a cork through which passes a 
fine glass tube to be connected with a tube, e, filled with chloride of calcium. 
The cylinder, A, is heated by a subjacent lamp, and a definite temperature 
thereby communicated to the air surrounding the matrass in the cylinder. 
The conducting tube, f, is brought into communication with an air-pump, 
and while the matrass with its contents is heated in the air bath, the air- 
pump from time to time extracts the moisture-charged air. The air which 
would return into the matrass on opening the air-pump, must first pass 
through the chloride of calcium, and will be there dried before it can enter 
into B. 
By means of the apparatus just described, we are enabled to separate the 
water from any body whether chemically or mechanically combined with 
it. All the water being thus removed from the body, suppose the problem to 
be,to determine its remaining components. If sugar be the substance in 
question, take a certain amount and dry it in one of the ways just described. 
Pure oxyde of copper is next to be well heated in a crucible (pl. 31, fig. 
57), and the known weight of sugar mixed with it, after the covered 
crucible has been allowed to cool to 250-260° F. This mixture of oxyde 
of copper and sugar is to be introduced into a tube (jig. 29) from one half 
to two feet long, made of the most infusible glass, the lower end of which 
is drawn out into a fine closed point. As both the oxyde of copper and the 
sugar absorb fresh moisture during the mixture, this must first of all be 
again removed. This is done by the application of the air-pump (jig. 24). 
This pump, A, is made to communicate by a tube, B, with the chloride of 
calcium tube (fig. 25), this tube itself inserted air-tight by the help of a 
pierced cork, a (fig. 25). into the mouth of the tube (fig. 29), after it has 
been filled with the mixture of oxyde of copper and sugar. The tube, as 
shown in fig. 24, is placed in a box, I, E, and surrounded with sand previously 
heated to 250°. The heat of the sand is communicated to the tube, D, 
which contains the mixture, and the water previously absorbed becomes 
vaporized. By means of the air-pump, A, the air contained in D, and 
charged with vapor, is carried through the chloride of calcium tube, C, in 
which the vapor is retained. On opening the cock, a, of the air-pump, the 
air again enters the tube, D, perfectly dried by the chloride of calcium, and 
is charged afresh with moisture. In this way the mixture of the two 
substances in D becomes after a time perfectly dry. The tube, D, or the 
combustion tube, is now separated from the chloride of calcium tube, C, and 
laid in the combustion furnace (fig. 30). This is a box of sheet iron, about 
two to three feet long, and one half foot broad at the upper and open top, 
being somewhat narrower below. The bottom of this is seen in fig. 32, to 
be pierced transversely to permit the air to come in contact with the 
burning coals ; there are also notched transverse partitions, upon the edges 
of which the combustion tube is to rest, as seen in fig. 31; in this 
figure the anterior wall of the furnace, AA, is supposed to be removed. 
In the opening, b, of the combustion tube, DD, is inserted by means of a 
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