28 EXPERIMENTS IN BLUEBERRY CULTURE. 



tions of the various acids have the same degree of acidity. Normal 

 sohitions of alkaline substances are equal to each other in alkalinity. 

 A measured amount of a normal solution of an acid will exactly 

 neutralize an equal amount of a normal solution of an alkaline sub- 

 stance. 



In considering the degree of acidity from the standpoint of the 

 sense of taste it is convenient to remember that the juice of an ordi- 

 nary lemon is very nearly a normal solution of citric acid. The juice 

 of the lemon contains usually from 6 to 7 per cent of citric acid. A 

 normal solution of citric acid is 6.4 per cent. When the juice of a 

 lemon is diluted to about ten times its original bulk, as in a large 

 drinking glass, one has approximately a 0.1 normal acid solution. 

 When diluted to 100 times, making about a 0.01 normal solution, 

 there remains only a faint taste of acidity. The acidity of water 

 after standing long in contact with peat in a barrel sometimes reached 

 0.005 normal. Bog water, or peat water, is sometimes appreciably 

 acid to the taste. 



Returning now to a consideration of the statement that the swamp 

 blueberry does not thrive in a neutral or alkaline soil an experiment 

 in this direction may first be cited. The experiment was made with 

 twelve small glass pots, each containing a blueberry seedling. The 

 soil in the pots was a clean river sand. The plants had been in these 

 pots for eight weeks, watered with tap water. The amount of 

 nourishment they had received during this time was therefore very 

 small, especially since, when transplanted into the pots, all the soil 

 of the original seed bed had been carefully removed from the roots. 

 Nevertheless during these eight weeks all the plants had made exten- 

 sive, even luxuriant, root growth. The tops, however, had made no 

 growth. There had been complete stagnation or withering of the 

 youngest leaf rudiments, and the mature leaves became and remained 

 deeply purpled. 



Beginning on February 17, 1909, eight weeks after the plants had 

 been potted in the sand, as already stated, five of the pots were wa- 

 tered with an acid nutrient solution made up, in accordance Avith the 

 advice of Mr. Karl F. Kellerman, of the Bureau of Plant Industry, as 

 follows : 



Potassium nitrate (KNO3) 1. gram. 



Magnesium sulphate (MgS04) 0.4 gram. 



Calcium sulphate (CaS04) 0. 5 gram. 



Calcium monophosphate (CaH4P20s) 0.5 gram. 



Sodium chlorid (NaCl) 0. 5 gram. 



Ferric chlorid (FeCU) Trace. 



Water 1' <500 c. c. 



This solution gave an acidity test of 0.012 normal. 



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