10 2 THE SOURCE OF THE AMNIOTIC AND ALLANTOIC FLUIDS IN MAMMALS. 



solution, ignited in a porcelain crucible over a blowpipe, and weighed as magnesium 

 pyrophosphate. 



This, multiplied by the factor 0*21875, gave the proportion of magnesium compounds 

 expressed as Mg. 



Determination of Potassium and Sodium. 



A measured volume of the fluid was evaporated to dryness in a platinum basin and 

 carefully ignited over a low flame. The ash was dissolved in dilute hydrochloric acid 

 and filtered. The filter was ignited, dissolved in dilute hydrochloric acid, and the 

 solution filtered. 



The mixed filtrates were made alkaline with barium hydroxide solution, warmed for 

 some time and filtered. The filtrate was evaporated to small volume, and the excess of 

 barium removed by repeated treatment with ammonium carbonate and filtration. 

 Finally, the filtrate was acidified with hydrochloric acid, made alkaline with ammonia, 

 and evaporated to dryness. The ammonium salts were then burnt off in a platinum 

 basin at a low temperature, and the residue weighed. This residue was dissolved in 

 water and filtered. The filter was washed, burnt, and weighed, and its weight subtracted 

 from that of the undissolved residue. 



The resultant is the weight of the mixed alkali chlorides. 



The filtrate was treated with excess of hydrochloro-platinic acid, evaporated to 

 dryness on water-bath, treated with 85 per cent, alcohol, and filtered. The precipitate 

 was washed with 85 per cent, alcohol, and dissolved through the paper with boiling 

 distilled water. The solution was collected in a small weighed beaker, in which it was 

 carefully evaporated to dryness, dried at 130° C. and weighed. 



The weight of potassium chloro-platinate thus obtained, multiplied by the factor 

 0"3056, gave the weight of potassium chloride. 



By deducting the weight of potassium chloride from the total weight of alkali 

 chlorides obtained above, the proportion of sodium chloride present was determined. 



The weight of potassium chloride found, multiplied by the factor 0*52479, gave the 

 proportion of potassium compounds expressed as K. 



The weight of sodium chloride found, multiplied by the factor 0*39401, gave the 

 proportion of sodium compounds expressed as Na. 



