II 



Total solids and ash were determined on the sap of the set of 1 2-9-14. 

 The results, given in Table VII, are calculated to milligrams per cc. of 

 sap. 



Table VII. — Total Solids and Ash op Sap. 



The average total solids content of the sap was 85 . i mg. per cc. and the 

 ash content 14.9 mg. The influence of the fertilizer applications 

 is seen in the increase in both values as the applications of any 

 fertilizer were increased in a series of sections. Sample 3 of the first set 

 and 6 and 7 of the second, all of which were from plants to which large 

 applications of potassium sulfate had been made, showed particularly 

 high values.*** The first set of data was obtained by drying the samples 

 in a Sargent electric oven at 60-70 °, the second in a vacuum oven heated 

 to 50° for 12 hours. The actual value for total solids depended on the 

 length of heating but experiments with both sets of data given showed the 

 same relative values after several successive heatings. 



* Ash determinations upon the sap were made by careful incineration of the solids 

 in I cc. of sap in platinum dishes over a low flame to prevent mechanical loss of particles 

 of the ash. The low chloride content obviates the danger of volatilization of potassium 

 chloride by high temperatures. 



** For some reason total solids and ash determinations always ran higher in sap 

 from plants in Section 283 than from those in other "check" sections. The same dis- 

 crepancy is seen in the osmotic pressure data for these two sets. 



*** The determination of total solids with accuracy is not possible on account of the 

 uncrystallizable solutes in the sap, and on this account the mean molecular-weight 

 calculations which often accompany osmotic pressure data were not made. Drying 

 on the water bath was found to cause charring of the sap from plants which had been 

 treated with ammonium or potassium sulfate. The first showed a higher acidity value, 

 the second a higher sugar content. 



