314 



Messrs. E. T. Glintlier and J. J. Manley. 



great changes have occurred in the interval between the bottling of the 

 samples in Persia and their examination in Magdalen College Labo- 

 ratory, in Oxford, seeing that the discrepancies between the analyses 

 are very small. 



The examination was both physical and chemical. 



Physical Examination. 



Determination of Specific Gravity. 



The specific gravities of the two samples of water (A and B) were 

 determined by Mr. H. N. Dickson, according to the method of Sprengel, 

 with the following mean results : — 



A. B. 



Specific gravity, at 15° C 1-11338 1-11389 



0-3° C 1-11891 1-11945 



Difference .. 0-00553 0-00556 



Determination of Refractive Index. 



The refractive indices (/x) were determined by means of a hollow 

 quartz prism of 60° 6' refracting angle, and a large spectrometer* 

 reading to 2" of arc. The water was at a temperature of 12 -2° C. 

 during the readings. 



A. B. 



Angle of minimum deviation of D line 25° 50' 4" 25° 50' 35", 



whence p = 1-36110 1-36122 



It is believed that similar optical measurements will be found to be 

 applicable to ordinary sea waters and will be found to give a more 

 accurate and a more readily obtained indication of the physical nature 

 of the water than the ordinary specific gravity methods. 



Determination of Boiling Point. 



It has long been customary to record the boiling points of strongly 

 saline natural waters, but in only too many cases, owing to the lack of 

 description of the conditions of the experiment, the records have only 

 a small value. Many trials have convinced us that the boiling points 

 of brines properly determined under similar conditions yield as reliable, 

 although less minute, information concerning the degree of salinity 

 as specific gravity determinations. 



The salt water was boiled in a platinum bottle, to which an inverted 

 condenser containing ice-cold water was attached, in order to prevent 



* The spectrometer, which was constructed for Dr. Bedson, and the prism em- 

 ployed are the property of the Royal Society. 



