38 Dr. Prout on the ultimate Composition 



On the platform, F F, (fig. 1.) is a thin piece of wood, capa- 

 ble of being raised or depressed at pleasure, by means of the 

 screws, OO; on this the lamp Q is placed, which may thus be 

 placed at any distance that may be required from the tube, P. 

 Fig. 3. is an enlarged view of this lamp: it consists of two 

 reservoirs, d e, for holding the spirit, connected together by 

 means of the tube, f, into which are placed, at the distance 

 from one another of about £ of an inch, a number of vertical 

 burners, g g, &c. about T ^ of an inch in diameter, and f inch 

 long, and made as thin as possible, with the view of preventing 

 the conduction of the heat. These burners are each furnished 

 with a few threads of cotton, and are bent a little alternately 

 like the teeth of a saw, in order that their flame may envelope 

 the tube, P, (fig. 1.) more completely, h is a cover for the wick 

 of the lamp when not in use. The tube, P, (fig. 1.) is of green 

 or bottle glass, moderately stout, and about £ of an inch in- 

 ternal diameter. It is fixed between the horizontal parts of 

 the vertical cocks, M M, so as to be perfectly air-tight; and 

 when required, the whole, or any part of it, may be heated 

 by means of the lamp, Q, at the pleasure of the operator. 



When the apparatus is to be employed, both the syphon 

 gasometers, I L, I L, are to be filled with quicksilver, and a 

 small green glass retort, containing the requisite quantity of 

 chlorate of potash, (and which had been previously heated so 

 as to completely expel the common air, and to fill it with 

 oxygen gas,) is to be attached to one of the cocks, as repre- 

 sented in fig. 4, by means of a caoutchouc tube. Heat is then 

 to be applied, and any quantity of oxygen gas that may be re- 

 quired, introduced into the tube, I. After the whole has ac- 

 quired the temperature of the atmosphere, the exact quantity 

 of the gas is to be accurately noticed, as well as the state of 

 the barometer and thermometer at the same time. The tube, 

 P, containing the substance to be analysed, is then to be firmly 

 fixed between the cocks, M M, # and subjected to heat, during 

 which the oxygen gas is to be transferred from one syphon to 

 another, through the red hot tube, with any velocity that may 

 be required, and which may be regulated by means of one of 



the 



sented by the dotted lines, and may contain as much as 20 cubic inches of 

 gas. It much facilitates the process of determining the exact quantity of 

 gas contained in the apparatus, to have both legs of the syphon graduated, 

 which may be easily done so as to obviate the effects of capillary attraction 

 when the tubes are not both of the same calibre. 



* I have tried various modes of connecting the tube so as to insure its 

 being air-tight. Caoutchouc answers very well ; but the best substance I 

 have hitherto employed are slips of thin moistened hogs' bladder, tied on 

 very tightly with fine dry twine. The twine is then to be moistened also, 

 and the whole kept in this state till the end of the experiment. 



