THE JOURNAL OF PHARMACOLOGY. 105 



B. Solution of sodium acetate in acetic acid, prepared by dissolving 100 

 grammes of sodium acetate in 800 Cc. of water, adding 100 Cc. of 30 per 

 cent, acetic acid and enough water to make 1000 Cc. 



C. Solution of uranium nitrate or acetate, prepared by dissolving 35 

 grammes of crystalline uranium acetate or nitrate in enough water to 

 make one liter. 



D. Solution of potassium ferro-cyanide in water (10 : 100). 



The exact titre of the uranium acetate or nitrate solution must be 

 established in each case. This is accomplished as follows : 50 Cc. of the 

 sodium phosphate solution are placed in an Erlenmeyer flask, 5 Cc. of the 

 sodium acetate solution added, and the whole heated to boiling. To the hot 

 liquid add the uranium solution, from a burette, as long as a precipitate 

 forms. At the latter end, the uranium solution is added Y-z Cc. at a time, 

 testing after each addition, with potassium -ferro-cyanide. This testing is 

 done as follows : A few drops of the indicator (potassium-ferro-cyanide 

 solution) are placed on a white porcelain surface, and by means of a glass 

 rod, a drop of the liquid in the Erlenmeyer flask is brought in contact 

 with them. The appearance of a pale red-brown color at the point of con- 

 tact indicates the end reaction. The operation should then be repeated, 

 for verification, using the same number of Cc. of uranium solution, as at 

 the first trial. Malot recommends the use of tincture of cochineal as indi- 

 cator. This strikes with uranium salts at first a bluish green color, which 

 when the end reaction is reached turns to pale green. The mixture must 

 be kept hot and shaken from time to time. 



The uranium solution which is always made more concentrated than 

 required, must now be diluted, in accordance with the results of the trial 

 just made. This must be done in such a manner, that 20 Cc. of it are the 

 exact equivalent of 50 Cc. of the sodium phosphate solution. Expressed 

 as PaO.^, 20 Cc. of it are the equivalent of o.i gramme of P0O5 or i Cc. 

 the equivalent of .005 P 2 O. 5. Example : 50 Cc of sodium phosphate so- 

 lution required 19 Cc. of uranium nitrate solution, consequently i Cc= of 

 water must be added for each 19 Cc. of uranium nitrate solution. In case 

 more than 20 Cc of uranium nitrate solution were required to complete 

 the reaction, then the solution must be concentrated to the proper 



degree. 



Procedure in case of urine. This is done in precisely the same manner 

 as above, 50 Cc. of urine and 5 Cc. of sodium acetate solution are titrated 

 while hot, with uranium nitrate solution. Each Cc. of the latter repre- 

 senting 0.005 grammes of P2O5. 



The sample of urine employed must be free from albumin. If this is 

 not the case, it is evaporated to dryness, the residue mixed with potas- 

 sium nitrate and sodium carbonate and ashed. The ash is then extracted 

 with hot water, after which proceed same as above. 



