lO Mr. Tovey*s Researches in the Uiidulatory Theory: 



tricians are denominated si^^j^z/ZflT. Besides, this partial free- 

 zing could scarcely take place without causing the freezing of 

 almost the entire mass. The coincidence also which exists 

 between the experiments performed on the same solution, but 

 with different tubes, excludes all idea of freezing. Thus, for 

 the solution of sea salt at 0°'0371, one tube gave — 4'°*80, 

 —4°' 73, — 4°*76, the mean of which is — •4'°'76. A second 

 tube gave —4°* 73, •—4°* 72, — 4°-77, the mean of which is 

 — 4°' 74, ; which differs from the first only by two hundredths. 



We conceive that there does not always exist the same 

 agreement in the partial experiments ; many however exhibit 

 but a small difference. 



In comparing the various experiments, we see that it is 

 neither the more soluble salts, nor the salts which most retard 

 the freezing point, that lower the maximum most; for instance, 

 the chloride of calcium lowers the maximum much less than 

 sea salt ; the sulphate of potash less than the sulphate of soda. 

 This result is obtained whatever may be the degree of con- 

 centration of the solutions compared. 



The two following results, says Despretz, appear to me to 

 be proved : 



1. Sea water, and all aqueous solutions, acid, alcoholic, sa- 

 line and alkaline, have a maximum of density. 



2. This maximum sinks much quicker than the freezing 

 point, the variation of which, as well as that of the density, is 

 nearly proportional to the quantity of matter added to the 

 water. 



The point of the maximum remains at first above that of 

 the freezing point; it then reaches it, and finally sinks below 

 it. Even with seven hundredths of salt, acid, or alkali, the 

 maximum may be at 12 degrees below the freezing point, so 

 that it is impossible to discover it except by exposing the fluid 

 solution in narrow tubes to temperatures far below that point. 



II. Continuation of Researches in the TJndulatory Theory of 

 Light; — On the Cause of Elliptical Polarization, By 

 John Tovey, Esq, 



To the Editors of the Philosophical Magazi?ie and Journal, 



Gentlemen, 



TN continuation of my Researches in the Undulatory Theory 

 -"- of Light, I submit to you the following investigation, 

 showing mechanically the cause of elliptical polarization. In 

 integrating the equations of this theory it has hitherto been 



