73 



Tile analytical data obtained from an examination of the DisiicliUs 

 spkaia — Samples I, II, and III — are given in Table XVI. The most 

 strikiniT point bronght out is the very large amount of acid shown to 

 be on Sample I, amounting for 1 gram of the air-dried material to 

 the equivalent of 23 cubic centimeters of a twentieth normal (X 20) 

 acid. This substance was unquestionably an organic acid and a 

 fairly strong one. It did not appear to act on crystals of calcite very 

 readily. This might have been due, however, to the formation of a 

 slightly soluble lime salt, which would protect the calcite from the 

 solvent. The acid very readily decomposed the alkali carbonates and 

 neutralized not only ammonium liydrat^ but x^otassium or sodium 

 hydroxide in the presence of cochineal or phenolphthalein as indi- 

 cator. It will be seen by referring to the analytical figures that a 

 large amount of sodium is left after balancing the acids by the bases 

 found. This would seem to find its readiest exfjlanation in supposing 

 that there was a much greater quantity of the organic acid on the 

 plant than indicated by the equivalent of 23 cubic centimeters of 

 twentieth normal acid, but present in the form of the sodium or other 

 salts. By referring to the analysis (Table XVII) of the soil from which 

 thi> Sample I oiDisficltlis spicatawixs taken, it will be seen that there 

 was relatively a very lai-ge amount of soluble carl)onates present, 

 about 2 per cent of the soil being composed of these substances — an 

 amount which would absolutely i)rohil)it the growth of any ordinary 

 plant, even though much of the salt was in the form of bicarbonate. 

 Much of this material probably came in contact with the grass leaves, 

 in the form of dust or otherwise, with the result that the acid decom- 

 posed the carbonates with the formation_o| salts of the organic acid. 

 These same views seem to hold for Samples II and III as well, but to 

 a lesser extent, as is shown by the quantitative measurements given. 



It would ai)pear from what could be learned in the field that this 

 grass, in the locality from which Sami)les II and III were taken, often 

 carries as much of the acid material as Sample I shows, or even more. 

 Unfortunately for this investigation the most favorable season for 

 securing sami^les had i)assed before Samples II and III were gathered 

 an<l .sent in. This subject will receive more careful attention during 

 another field season. 



ISOLATION AND IDENTIFICATION OF ACID EXU'DATION. 



Careful attempts were made to isolate or at least to identify this 

 organic acid, but the attemj^ts proved unavailing for several reasons. 

 But very little material was at command when the investigation was 

 taken up. The relatively large amounts of inorganic salts obtained 

 in the water extracts could not be well separated and presented great 

 analytical difficulties in the attempts to isolate so small a quantity of 

 the acid as was at our disposal. Attempts to cry.stallize tlie material 

 from solution, either as the acid itself or as a salt, proved disastrous 



