178 B. Bunsen — Cahrimetric Investigations. 



As the ice cylinder wliich surrounds the vessel a weighs 

 forty to fifty grams, and it is necessary, on the average, to melt 

 by each experiment only about 0-35 grams of ice, wMcli cor- 

 responds to rather more than four hundred scale divisions, it is 

 possible to make with the same ice cylinder as many as 100 dif- 

 ferent calorimetric determinations and to use the apparatus, ar- 

 ranged once for all, for weeks at a time, when care has been 

 taken that the snow which surrounds the 

 and evening renewed by refilling. 



The ice cylinder may be easily prod....^ ..^ - . 

 which is rendered intelligible by fig. 2 : A is a sheet 

 containing alcohol, B an empty" one, both of which are cooieu 

 to about -20° C. in a freezing mixture of salt and snow. C 

 represents the inner vessel a fig. 1, around which the ice cylin- 

 der is to be produced. If suction be applied to the tube a, the 

 cooled alcohol of the vessel A will be carried through the ves- 

 sel C into the vessel B ; if suction be then applied in the oppo- 

 site direction by means of the tube h, the alcohol will return 

 through the vessel C into the vessel A. By alternate suction 

 at a and h, the vessel C may be kept to the height a as long 

 as desired at a temperature of -10° C. to -16" C, by means ot 

 continually renewed cooled alcohol, and the required ice envel- 

 ^P® ^}\ be produced in the water mass surrounding the vessel 



which IS denoted in fig. 1 by h. I have given this ice-pro- 

 ducmg apparatus the form, fig. 3. The two semi-cylindrical tn 

 vessels a and 5, which communicate with one another and with 

 the tube a by means of tubes above and below, correspond to 

 the single vessel A fig. 2, the precisely similar tin vessels oppo- 

 site these, the outer one of which is denoted by c, correspond 

 to the vessel B in fig. 2. These two vessels, each consisting ot 

 two concentric chambere, together with the tube a, possess, a^ 

 may be seen, a veiy large cooling surface, and are sunk in one 

 and the same freezing mixture. The arrangement of the sys- 

 tem of tubes, fig. 3, by means of which the circulation of tbe 

 cooled alcohol is efi'ected, is rendered easy of comprehension, 

 from the fact that the corresponding rubber tubes are designated 

 by the same letters as in fig. 2. The alternate suction to am 

 fro of the alcohol is regulated by the alternating cock H, whicb 

 communicates with the water air-pump by means of the nibb 

 tube IV. When this cock is in the one position the rabber tube 

 ?commumcates with the suction tube m;, the tube i? however 

 with the atmosphere ; in the other position the order is reversed 

 nJ^''^^'' ^^^ ^ communicates with the rubber tubei), and 

 7 with the outer air. By means of this contrivance, the pr*> 

 duction of the ice cylinder becomes a very simple operation 



1 he coolmg apparatus with its attached rubber tubes is pl^c^ 

 m the freezing mixture, p and q are connected with the alter- 

 nating cock H, w mth the water air-pump, the rubber stoppe-^ 



