RESEARCH METHODS IN STUDY OF FOREST ENVIRONMENT. 133 
which barium chloride has been added is left to stand for several 
hours. 
3. One hundred cubic centimeters for determining P 2 5 (phos- 
phorus pentoxide). 
In ordjer to determine the presence of phosphorus pentoxide 
(P 2 5 ), 100 cubic centimeters of the solution is neutralized with 
ammonia until an odor is perceived, the solution is made acid by 
the addition of weak nitric acid (HN0 3 ), and to such acid solution 
there is added from 10 to 15 cubic centimeters of molybdic acid 
(H 2 Mo0 4 ). 
A qualitative test for ferric oxide can be made in the water solu- 
tion of the soil by hydrochloric acid. Some hydrochloric acid is 
added, together with several drops of potassium sulpho cyanide 
(KSCX). A pink, or often bright red, color will indicate the pres- 
ence of ferric oxide in the solution. When the soil is rich in ferrous 
oxides, their presence can be readily ascertained by dropping directly 
upon the soil some of the potassium ferricyanide (K 3 Fe(CN) 6 ) solu- 
tion which with the ferrous oxides gives a blue color. 
The form for the " Summary of Physical and Chemical Properties 
of Soil " is provided with a number of blank spaces in which the 
results of qualitative or quantitative tests for various salts may be 
entered. 
