Tue NATURE AND REACTION OF WATER FROM HyDATHODES 5 
PRESENCE OF CERTAIN INORGANIC MATERIALS IN WATER FROM HYDATHODES 
Total solids 
In making a determination of the inorganic as well as the organic 
materials in the exuded water, it was desirable to know the proportion of 
each. This was determined by evaporating 10 cubic centimeters of the 
water and weighing the residue both before and after igniting it. The 
material which was left after ignition was called inorganic, while that which 
was driven off on ignition was called organic. The results of three deter- 
minations are given in table 1: ; 
TABLE 1. Torat Sormps anp ORGANIC MatreR IN WATER FROM HYDATHODES 
Total solids Parts per Parts per 
Source of water (parts per million left million lost 
: million) after ignition | on ignition 
INon-stenilesmalzem. oa. eco ges oh lets ee 1,030 280 750 
SHS HONTUIY? sacle Ace IIE RE ECS 573 377 196 
SUMS Tint OU Oy oS obo ee eee eee 220 90 | 130 
These results indicate that there was a considerable variation in total 
solids of various collections; also, that the amount lost on ignition, which 
was called organic matter, varied from 130 to 750 parts per million. This 
variation may be due partly to the fact that plants of different ages 
were used. 
Nitrites 
To about 5 cubic centimeters of the exudate water from maize plants 
forty-three days old, the Griess reagents for the detection of nitrites were 
added. After a few minutes a pink color began to appear. At the end of 
twenty minutes the color was very pronounced but was much fainter than 
that of a standard which represented 0.0001 milligram of nitrites per cubic 
centimeter. The reagents did not give this test with distilled water. 
In a second test, from three to four drops of an aqueous solution of 
0.2 per cent sulfanilic acid was added to 4 cubic centimeters of the exudate 
water from maize plants forty-three days old, and the materials were 
mixed. From two to three drops of concentrated hydrochloric acid 
and an alcoholic diphenylamine solution was added to this mixture. 
When these were mixed, the red color that appeared was taken as an 
indication of nitrites. The reagents and distilled water did not give this test. 
A third test for nitrites consisted in adding an alcoholic solution of 
alpha-naphthylamine and dilute hydrochloric acid to some of the exudate 
water, the development of a deep violet being considered a positive 
test for this constituent. 
Exudate water from sterile maize, oats, and timothy, from eight to 
eighteen days old, gave these tests for nitrites. 
Nitrates 
To test for nitrates, 5 cubic centimeters of the exudate water from 
maize was evaporated to dryness, and to the residue was added 0.1 cubic 
