80 
H. S. H. WARDLAW. 
Table II. 
Amounts of P,O; found in 10 cc. of milk by Newmann’s method. 
Result A. Difference. 
Estimation. Result B. 
1:0 mg. 
0:4 mg. 
—= OH OH CONG 1 
bo bo bo bo bo 
oe NWwWe 
bD b> bO & bO bb bo 
bo SS OUbS bo 
ow ow oO WwW o© 
1 
1 
The maximum difference between any two of the results 
in this table is 2°2 mg.; the average difference between two 
estimations is 0°8 mg. 
(b) Standard phosphate solution.—The standard solutions 
of phosphate were prepared by dissolving 6°6 gm. of micro- 
cosmic salt in water and making the solutions up to one 
litre. These solutions have about the same concentration 
of P.O; as milk. The solutions were standardised either 
(a) by evaporating a known volume of the solution to dry- 
ness in a weighed crucible, igniting, and weighing the 
sodium metaphosphate formed, or (b) by estimating the 
amount of phosphate present by the magnesia mixture 
method. The values obtained by the two methods agree 
together as closely as the individual estimations of either 
method, as the following figures for solution A (about 3°3 gm. 
of microcosmic salt per litre) show :— 
Table ITT. 
Standardisation of Phosphate Solution. 
ig Wei f i . 
Volume of |" Weigicot | weet) ae ee 
40 ce 0:0349 gm. 0:0484 gm. | 0:02420 gm. 
40 ,, 0:0351 ,, adi 0:0487 ,, | 0°02435_,, 
5 er gi 0:0574 gm. | 0°0366 ,, | 0:02436_,, 
30 ,, 00571 ,, |0°0364 ,, | 0°02426 ,, 
0s | 0-0576 ,, |0°0367 ,, | 0°02440 ,, 
