JR. Bunsen — Calorimetric Investigations. 349 



prevent its rising, is twisted around a coiled platinum wire. 

 This cotton answers a double purpose : in the first place it pre- 

 vents the glass vessel from being injured bj the falling in of 

 specifically lieavj bodies ; then in addition it aids in the removal 

 from the apparatus of the substances which have been used in 

 the experiment. To effect this, a properly bent wire is bored 

 into the cotton, which, with the substance resting upon it, is 

 drawn therewith to the mouth of the tube, the substance is re- 

 moved and the cotton without being taken out of the vessel is 

 returned by means of the wire to its former place, 

 The principal advantage, which, independent of its great del- 

 t just described possesses over all other cal- 

 that the entire heat which the heated 



ijoily evolves is employed, without any loss, in the ice melting: 

 the weights of the substances which give up their heat to the 0° C. 

 cooled water of the vessel a, fig. 1, is so small compared with 

 the weight of this water, that the temperature can never rise to 

 * C. As the water has at this temperature its maximum den- 

 sity, the fluid which warms itself on the bottom of the vessel a 

 can never rise, and is protected from every loss of heat, not 

 employed in ice melting, by a high superincumbent water 

 column at 0° Q, whose conducting capacity for heat is vanish- 

 ingly smaU. This circumstance may be observed very beauti- 

 fully on the ice cylinder, when it has been used for 30 to 40 

 experiments. There is then to be found in the ice, quite far 

 down on the bottom, where the vessel a is rounded off, a hol- 

 ow space, melted out and filled with water, which possesses 

 tne very regular form of a small glass matrass, while the ice 

 cyhnder above this part appears throusrhout its whole extent 

 entirely unaltered. 



The weight of the substance to be investigated need be, ac- 

 cordmg to the specific heat to be expected, no greater than O'S 

 pams, to at most 4 grams. If the substance is a fluid, or if it 

 i* subject to alteration by the access of air or water, it is, as in 

 'lr^^^^° analysis, sealed in the lightest possible gla; 

 ubstanc( 



^M of platinum wire, heavy enough to effect the in..^^.^.^^. 

 f ^oiild probably be still more convenient to employ in all 

 hp ? '\^'^^^' *^S^t^3^ closing platinum vessel. The amount of 

 in ^r^ the glass case and platinum spiral emit is mcluded 

 the D-1 ^^^^^^^*j*^^ ^» the Jbllowing manner: Let the weight of 

 I teat, mea 

 class of the , 



