Atomic Volume and Specific Gravity. 



459 



iooccupied by 172 grains, or one equivalent of sugar, in solu- 

 -rtioiis of different degrees of density, 

 sdj JBiij 8iii'iqqr> j- ^. ; ,, 



i>Iofl 83of) ji f'ft jfi/tr, , , ., , Table. L 



Mi'-.,''ii .i.i.i i; 



Ratio ~6f tHe quantity of sugiit to 



the quantity of water 



in which it was dissolved. 



r ,- :m\ uJ: 120: ■ 

 d'UA(|/?;n 



noijrjlii{ |i io i,^,:,, 



TemperataM. 



60 



62 

 52 



62 



k'iij 



ji(; Volume in 



.girain measures 

 :<)'■ of water. 



9900 

 105-09 

 107-01 

 108-06 



jjioUiyiiji. 



ifili/riic 



srii JaJ 



y;Ji8n9b 



; ■"O-i- M, . . 



-.1^ fAs the rate of expansion of dilute solutions is so near that 

 of water, it was in most cases sufficient, for a very close ap- 

 proximation to absolute accuracy, to take the observation 

 within a few^ degrees below 60°, the temperature of the gra- 

 duation of our volumenometers. Whether this temperature of 

 graduation is the best to adopt, is a point which we shall have 

 to discuss in our future communications ; but at present it 

 may be sufficient to state that its convenience was considerable, 

 as being the average temperature of our laboratories. In all 

 cases, then, in the following experiments, unless where it is 

 otherwise stated, tlie temperature of the solution was about 

 60°, which was also, of course, the temperature of the water 

 before the salt was introduced. In the case of the sulphates 

 of the magnesian class of metals, the temperature chosen was 

 higher than 60°, in order to make up for a diminished rate 

 of expansion, owing to a greater degree of dilution in the 

 solution. 



The specific gravity of the salts was determined in an equally 

 simple manner. A saturated solution of the salt about to be 

 experimented upon (made l)y dissolving an excess of the salt 

 by heat and allowing the solution to cool) was placed in the 

 apparatus already described, and a weighed portion of the 

 salt was then introduced, care being taken that the tempera- 

 ture did not vary during the experiment. As the new por- 

 tion of salt could not dissolve, the increase in the stem indi- 

 cated the volume due to the quantity of salt introduced, and 

 afforded data for calculating the specific gravity. In many 



v.'.cases oil of turpentine was used instead of the saline solution* 

 It was frequently desirable^ especially in the case of hydrated 

 salts rendered anhydrous, to avoid the use of water, and in 

 the case of organic compounds, also of turpentine; and to 

 meet such cases we constructed the following simple appa- 

 ratus, which we believe to possess various advantages. 



2H2 



