JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. io APRII, 19, 1920 No. 8 



CH'EMIST'RY .—Determining soil acidity and alkalinity by in- 

 dicators in the field. ^ Edgar T. Wherry, Washington, D. C. 



About a year ago the writer^ recorded a series of tests on 

 soil acidity and alkahnity made by the indicator method'' in 

 the laboratory, the soil samples having been collected from sta- 

 tions where forty species of native orchids grew. These sam- 

 ples exhibited such characteristic differences in reaction that it 

 seemed worth while to study other groups of plants in a similar 

 manner. The bringing in of samples of soil in sufhcient number 

 to make the results significant would have involved, however, 

 carrying numerous containers on field trips. It was, therefore, 

 decided to work out a method for applying the tests in the 

 field, so that only a few bottles of indicator solutions would have 

 to be carried along. 



The following outfit proved to fill the requirements.^ First, 

 a rectangular box about 3.5 X 5 X 9 cm. in dimensions. In 

 the box, six vials for the indicators, 1.5 X 5.5 cm., capacity 

 8 cc, each provided with a cork or rubber stopper, into which is 

 inserted a glass rod flush with the top of the stopper, and ex- 

 tending nearly to the bottom of the vial; to prevent undue com- 

 pression upon inserting the stoppers, a groove may be cut in 

 the side of each, so as to reach nearly to the lip of the vial. 

 Then, three or four vials 'in which to extract the soils, about 



' Received February 5, 1920. 



2 This Journal 8: 589. 1918. 



^ Clark and Lubs. Journ. Bacteriology 2: i. 191 7. Gillespie. This 

 JoimNAL 6: 7. 1916. 



^ Sets of indicators similar to that here described are for sale by the La Motte 

 Chemical Products Co., 13 W. Saratoga St., Baltimore, Md. 



217 



