1016 On the spontaneous heating of Brine. [Dec. 



to have undergone no change at all, with respect to the degree of saltness, 

 in seven months from June to January, when, (allowing for an error in 

 the hydrometer which will presently be noticed,) the S. G. was found to 

 be the same as when the water was let in at the end of May and begin- 

 ning of June. 



The tables I now exhibit shew the specific gravities as well as th« 

 temperatures in all cases in which the hydrometer was used, and may 

 be thought unnecessarily voluminous on that account. But as the object 

 is to give opportunity to investigate the cause of the heating, I have 

 thought it advisable to suppress nothing ; the S. G. columns, though 

 some of them apparently mere repetitions, being to a certain extent a 

 test of the manner in which the probe was charged. Nor have I omitted 

 those trials which turned out unsatisfactory from the probe having been 

 drawn up too soon, or in which error occurred, taking care however to 

 insert a note thereof. The disparity in the number of joints of the 

 probe filled at different trials, in the same depth of water, was owing to 

 greater or less inclination of the instrument. 



The probe used in these experiments, instead of the machine before 

 described which was rather inconvenient to handle, was a thick bamboo 

 with a hole cut across at the top of every joint, large enough to admit 

 a small thermometer to try the temperature, and a small hole plugged 

 at the bottom of every joint to draw off the water for trial by the hy- 

 drometer. By covering the large holes with soft paper and letting the 

 bamboo remain in the water till the air bubbles (after the bursting of 

 the paper) had ceased to rise, I have procured water of the different 

 strata corresponding with the numbers of the joints, without mixture ; 

 but this method occupied so much time that I did not think it worth 

 while to be so particular as to the degrees of saltness, which conse- 

 quently in the lower numbers will be found registered somewhat below 

 their actual condition, the reduction being in proportion to the depth 

 and specific gravity of the weaker brine near the surface. Each set of 

 salt works was furnished with one of these probes. The Bally a 

 Ghat probe was a bamboo with joints of nearly equal length through- 

 out, averaging sixteen inches each. The joints of the Bhaota and 

 Narainpore probes were more unequal, their several lengths being as 

 follows respectively, measured from the bottom upwards. 



