76 H. S. H, WARDLAW. 
and Bayliss also wash the precipitate in a different way; 
they use suction and water at ordinary temperatures, and 
are able to complete the washing in five minutes. Gregersen 
recommends precipitating in the presence of 15% ammonium 
nitrate instead of 10%, and states that there is a lower as 
well as an upper limit to the amount of sulphuric acid 
which may be present in the acid-ash. He also calls atten- 
tion to a point of some importance which was overlooked 
by Neumann, that is, that it is necessary to eliminate car- 
bon dioxide from the solution before the final titration; 
neglect of this leads to errors of several tenths of a cubic 
centimetre in the titration. 
J have only been able to find one set of control experi- 
ments on Neumann’s method showilg really satisfactory 
results; this occurs in Gregersen’s paper mentioned above. 
Neumann’s own paper gives extremely few control experi- 
ments. Another series of control experiments published 
by Plimmer and Bayliss shows variations amounting to as 
much as 5%, yet on the basis of these results the authors 
describe the method as extremely accurate. Donath gives 
a set of control estimations showing variations of the same 
extent, and describes the method as elegant. Mathison 
makes the statement that on K, HPO, Neumann’s method 
gave results agreeing to 17% with those obtained by the 
magnesia mixture method. Ehrstrom on the other hand 
states that the method sometimes gives inaccurate results 
for no apparent reason. In a recent paper by Haslam 
figures are given which go to show that in the determin- 
ation of very small amounts of phosphorus (less than one 
milligram) Neumann’s method may give results of higher 
accuracy than those obtainable by the usual methods of 
analysis. As, however, Neumann’s method is one which 
is coming into general use for all classes of biochemical 
work, it seems that more detailed information as to the 
