Abstract
The moisture content of expressed plant saps can be measured by determining the refractive index of the sap using an Abbé refractometer provided with a special “sugar scale.”
In a series of determinations we have found that more accurate results can be obtained by the refractometric method than can be obtained by drying weighed portions of the saps in a vacuum oven. The results are fully as accurate as are those obtained by drying in vacuo at room temperature over sulfuric acid.
The great advantage of the method lies in the fact that only 2 or 3 drops of sap are necessary and that the entire time of measurement need not exceed two minutes.
It appears probable that the method may be applied to other biological fluids. A more extended account of the method will appear in a botanical journal.
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