88 G2. BASES AXD ACIDS WITH "EEAGE^sTS. 



tion of the standard pliosphatic solution, and locate the 

 point of saturation more accurately between 16 and 17 

 cubic centimetres, beginning with 16.1 c.c. and so on. 



If we find, finally, that 25 c.c. of the standard phos- 

 phatic solution requires 16.5 c.c. of the uranic solution for 

 the complete precipitation of the phosphoric acid, then, 

 evidently, to every 16.5 c.c. of the former, 8.5 c.c. of pure 

 water must be added, in order to make a standard uranic 

 solution, each cubic centimetre of which shall be exactly 

 equivalent to 0.005 grm. of phosphoric anhydride. 



The respective quantities of uranic solution and wa^r 

 being carefully measured out and mixed, for making half 

 a litre or a litre of the standard solution, this solution 

 should be tested, in order to be sure of its value with 

 respect to phosphoric acid. Dilute 5 c.c. of the standLirl 

 phosphatic solution, add 1-2 c.c. of sodic acetate, and 

 then add the uranic solution from a burette graduated into 

 ^ Ijq cubic centimetres ; exactly 5 c.c, not a tenth more or 

 less, should be required before the reaction with the ferro- 

 cyanide is given. 



The method of determining phosphoric acid volumet- 

 rically, with the aid of this standard uranic solution, is 

 the same as that just described for the determination of 

 the strength of this solution as originally prepared. The 

 amount of phosphoric anhydride in the quantity of tlie 

 solution taken is then given, by the product of 0.005 

 into the number of cubic centimetres of standard uranic 

 solution required to precipitate the acid. 



NITRIC ACID. IINO3. 63. 



62* AH nitrates are soluble in water. 



Reactions. — If a nitrate is heated with concentrated 

 sulphuric acid and copper turnings, red fumes of nitric 

 peroxide, NO^, become visible in the upper part of the 



