30 CHEMISTRY. 
dry cork, a chloride of calcium tube, a (pl. 31, fig. 26), filled to cc, or else 
the simple chloride of calcium tube (figs. 27 and 28), as also figs. 30, 31. 
To this tube again is fixed the so called potash apparatus, F (jig. 30). 
This consists of a glass tube in which five bulbs are blown and arranged, as 
shown in the figure. The three bulbs lying ina row are filled with solution 
of potassa by dipping one end, c (fig. 39), into a vessel, H, containing 
solution of potassa, and sucking up the ley by means of the sucking tube, 
G, attached to the other end. When the potash apparatus is filled with ley, 
it is attached to the chloride of calcium tube, E (fig. 30), by a caoutchouc 
tube, c. Finally the combustion tube, D, is gradually surrounded entirely 
with burning coals, applied first anteriorly and then with great caution 
along the tube. The entire arrangement has the following end in view: 
The oxyde of copper with which the sugar has been mixed, gives off, as 
soon as it has been heated to redness in the combustion tube, its oxygen to 
the carbon and hydrogen of the sugar, forming with the former, carbonic 
acid, and with the latter, water. The oxygen naturally contained in the 
sugar likewise combines with the two other elements. The oxygen and 
hydrogen then of the sugar, together with the oxygen of the copper, all 
enter into combination, and are entirely converted into watery vapor and 
carbonic acid. Both of these substances converted into gas by the heat, 
pass over into the chloride of calcium tube, E. A great portion of the 
watery vapor readily condenses by communication with the air, and collects 
in the bulb a; the remainder is entirely abstracted by the chloride of 
calcium filling the apparatus to c, c, fig. 26. The carbonic acid enters into 
the potash apparatus, in which it is entirely absorbed. The combustion 
tube, D, and the chloride of calcium tube, E, still contain some carbonic 
acid which must also be brought into the potash apparatus. For this 
purpose the fine point of the combustion tube is broken off, and over the 
aperture is placed a glass tube, C (fig. 31), open at both ends, and sustained 
by a holder, B. - The suction tube, G, or fig. 53, is applied to the potash 
apparatus, and a current of air drawn through the tube, C, into the 
combustion tube, DD, which gradually draws over into the potash apparatus 
the whole of the carbonic acid, there to be absorbed. The chloride of 
calcium tube, I, had been weighed before the operation ; it is now again 
to be weighed, when the excess of weight will express the amount of water 
which was formed from the hydrogen of the sugar in its combustion with 
the oxyde of copper. The potash apparatus has likely been previously 
weighed, and its excess after the experiment will be the amount of carbonic 
acid formed from the carbon of sugar. The combining numbers of both 
water and carbonic acid are already known; in nine parts by weight, water 
contains one part of hydrogen and eight of oxygen. The amount of water 
ascertained, divided by nine, .will give the amount of hydrogen contained in 
the given weight of sugar. Carbonic acid consists of three parts by weight 
of carbon and eight of oxygen ; multiplying the amount of carbonic acid as 
ascertained, by the fraction ,,, we shall have the amount of carbon 
contained in the sugar examined. Finally, by adding together these two 
amounts thus found, and subtracting from the known weight of the dried 
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