316 Messrs. E. T. Giinther and J. J. Manley. 



sodium phosphate instead of by ammonium phosphate as Dittmar 

 recommends, because when the latter reagent was used the magnesia was 

 found to come down very slowly and to adhere inconveniently to the 

 sides of the vessel. 



The soda was determined by the method in which all the bases are 

 converted into normal sulphates, and the weight of the mixed sul- 

 phates is diminished by the subtraction of the weights of the potas- 

 sium, calcium, and magnesium sulphates. The potash was determined 

 by precipitation from the mixed sulphates by chloride of platinum, 

 according to Dittmar's third and final method,' 55 ' and his observations 

 upon the appreciable solubility of the finely divided platinum by the 

 cold dilute hydrochloric acid employed for washing were confirmed. 



From the known amounts of lime, magnesia, and potash (see below) 

 were deduced the following weights of normal sulphates in 100 grams 

 of the mixed sulphates : — 



A. B. 

 Grams. Grams. 



Potassium sulphate 0'258 0-259 



Calcium sulphate 0-146 0-171 



Magnesium sulphate , 1 -870 1-871 



Sodium sulphate (by difference) ... 15*547 15*606 



Total sulphates 17*821 17*907 



The quantities of the principal saline components dissolved in 100 

 grams of the water of Lake Urmi are — 



A. B. 



Lime(CaO) : 0*0603 0-0706 



Magnesia (MgO) 0-6265 0*6266 



Potash (K 2 0) 0-1394 0*1402 



Soda(Na 2 0) 6*788 6*814 



Chlorine (CI) 8*496 8*536 



Sulphates (SO s ) 0*6205 0*6312 



16*7307 16*8186 



Oxygen equivalents of the chlor- 

 ine to be deducted 1*9167 1*9258 



Total salts in 100 grams of water 14*814 14*893 



* e Challenger Keports,' loc. cit., p. 16. 



