32 BULLETIN 1460, U. S. DEPARTMENT OF AGRICULTURE 
Boric acid solutions containing ammonia must be titrated within 
four hours in order to incur no losses of ammonia. 
Sodium thiosulphate is an acceptable substitute for sodium or 
potassium sulphide as a mercury precipitant. 
Careful attention should be given to standardizing normal solu- 
tions. Errors in terms of protein equal 0.35 per cent. The error 
in making such standards is much too large. 
The use of potassium acid phthalate as a standard solution is 
suggested. 
Careful attention must be given in the points brought out to 
assure concordant protein results by different chemists and different 
protein laboratories. 
ADDITIONAL COPIES 
OF THIS PUBLCATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT- 
5 CENTS PEE, COPY 
A 
