THE SOURCE OF THE AMNIOTIC AND ALLANTOIC FLUIDS IN MAMMALS. 101 



the filtrate was determined by means of standard ammonium thiocyanate solution, using 

 ferric sulphate solution as indicator. 



The difference between the amount of silver nitrate added and the amount found 

 after precipitation of chloride was calculated into the equivalent amount of chlorine. 



Determination of Total Sulphur. 



The total sulphur was determined by igniting with sodium carbonate and potassium 

 nitrate, dissolving the ash in dilute hydrochloric acid, and precipitating with barium 

 chloride solution. 



The weight of barium sulphate obtained, multiplied by the factor 0'41146, gave the 

 proportion of total sulphur expressed as S0 4 . 



Determination of Total Phosphorus. 



The total phosphorus was determined by igniting with sodium carbonate and 

 potassium nitrate, dissolving the ash in dilute nitric acid, and precipitating the boiling- 

 hot solution with a boiling-hot solution of ammonium molybdate in presence of 

 ammonium nitrate and nitric acid. 



The precipitated ammonium phospho-molybdate was filtered, washed with a mixture 

 of ammonium nitrate and nitric acid solutions, dissolved in ammonia, the solution 

 heated to the boiling-point, and the ammonium phospho-molybdate re-precipitated by 

 addition of boiling; -hot nitric acid solution. 



The precipitated ammonium phospho-molybdate was filtered through a Gooch's 

 crucible, washed with ammonium nitrate and nitric acid solution, and heated at 160° C. 

 until the weight was constant. 



The weight of ammonium phospho-molybdate found, multiplied by the factor 0*05022, 

 gave the proportion of total phosphorus expressed as P0 4 . 



Determination of Calcium and Magnesium. 



The ash from a portion of the fluid was dissolved in dilute hydrochloric acid, 

 filtered, warmed, made alkaline with ammonia, and then acidified with acetic acid. 



The calcium was precipitated by addition of ammonium oxalate, the mixture 

 heated for some time, and then filtered. The precipitate was ignited in a platinum 

 basin, then moistened with dilute sulphuric acid, dried, ignited, and weighed as 

 calcium sulphate. 



The weight of calcium sulphate, multiplied by 0*29450, gave the proportion of 

 calcium compounds expressed as Ca. 



In the filtrate from the calcium oxalate, the magnesium was precipitated by sodium 

 phosphate and ammonia as magnesium ammonium phosphate. 



After standing twenty-four hours this was filtered off, washed with dilute ammonia 



