Substances in the Solid State and in Aqueous Solut 



ion. 



40' 



t° t° 



All the densities given in Table B are ^-5, and not d jq. 



Those given under the names of Grerlach and Kremers are not 

 the direct results of observation, like those of Thomsen and 

 Nicol. TTe have calculated them from other experiments of the 

 two observers; and we shall return later on to this calculation. 

 These densities have been added to the table to fill up gaps in 

 Thomsen's experiments. We have nothing to add concerning 

 the compounds of potassium and sodium ; we therefore pass 

 on to an analogous case. 



Analogous Compounds of Fluorine and Chlorine. 

 It may have already been remarked, in Table A, how great 

 the specific gravities of KF and NaF are, compared with the 

 analogous compounds KC1 and NaCl. In reality this case 

 bears a strong resemblance to the one we have just been ex- 

 amining. The compounds of fluorine, of which the molecular 

 weights are smaller than those of the analogous compounds of 

 chlorine, have greater specific gravities ; the difference in the 

 molecular weights CI — F is nearly equal to that between 

 K— Na ; being for CI— F = 16*5 for one molecule, 33 for two 

 molecules, and 49*5 for three molecules. However, the spe- 

 cific gravities of the fluorine compounds are greater than those 

 of the chlorine compounds ; and the difference is about three 

 times more than in our first case : this will be evident on 

 referring to Table C. 



Table C. 

 Specific Gravities, at the ordinary temperature, of the analo- 

 gous compounds of Fluorine and Chlorine. 



Example. 



Fluorine 

 compound. 



Specific 

 gravity. 



Chlorine 

 compound. 



Specific 

 gravity. 



Eatio of 



specific 



gravities. 



1 



2 



3 



4 



5 



6 



7 



8 



LiF 

 NaF 

 KF 



MgF 2 

 CaF 2 

 BaF 2 

 PbF 2 



AsF 3 



2-60 



2-77 , 

 2-48 



2-47 



3-18 

 4-83 

 8-24 



2-67 



LiCl 

 ]S T aCl 

 KC1 



MgCl 2 

 0aCl 2 

 BaCl 2 

 PbCl 2 



AsCl 3 



204 

 2-15 

 1-98 



218 

 2-22 

 3-85 

 5-80 



2-20 



1-275 

 1-289 

 1-253 



1-133 

 1-433 

 1-254 

 1-421 



1-284 



Mean ratio 



1-293 



The two compounds of arsenic, AsF 3 and AsCl 3 , 

 know, liquid at the ordinary temperature. 



It may be asked, in what way does the phenomenon present 

 itself in solutions ; which of the two solutions has the greater 



