278  Effect  upon  Acidity  of  Tomato  Fruits.  \  Am-^-^vm- 
with  150  Cc.  distilled  water,  employing  for  each  titration  25  Cc.  of 
this  solution  diluted  with  distilled  water  to  50  Cc.,  and  titrating  with 
n/10  NaOH,  using  phenolphthalein  as  indicator.  Not  less  than 
two  titrations  were  made  in  any  case,  and  these  were  from  one  or 
more  samples  of  tissue.  The  accompanying  table  indicates  the 
variety  and  condition  of  the  fruit,  quantities  of  n/10  NaOH  required 
to  neutralize,  and  the  per  cent,  of  acidity  in  terms  of  citric  acid. 
TABLE  SHOWING  ACID  CONTENT  OF  TOMATO  FRUITS 
Variety- 
Condition 
Average 
number  of 
Cc.  of  n/10 
NaOH,  to 
neutralize 
Total  per 
cent,  of 
acid  as 
citric 
When 
picked 
Interval 
or  incubation 
When 
titrated  * 
Dwarf  Stone  
Dwarf  Stone  
Ripe 
Half  grown 
Half  grown 
Half  grown 
Half  grown 
0 
0 
Incub.  320  C.  10  days 
Lab.  24  days 
Incub.  320  C.  10  days 
Red 
Green 
Artif.  yellow 
Red 
Green 
1.695 
1.82 
2.135 
1-375 
1.485 
•  52 
•  56 
.66 
.42 
.46 
Sparks's  Earliana.  . 
Sparks's  Earliana. . 
Ripe 
Half  grown 
0 
0 
Red 
Green 
1.695 
1.87 
•  52 
•  58 
Truckers'  Favorite. 
Truckers'  Favorite. 
Half  grown 
Half  grown 
Incub.  320  C.  22  days 
Lab.  24  days 
Artif.  yellow 
Red 
2.56 
1.66 
.79 
.51 
Half  grown 
Half  grown 
Incub. 32°C.22days 
Lab.  24  days 
Artif.  yellow 
Red 
2. 115 
1-675 
.65 
•  52 
Yellow  Peach  
Half  grown 
Half  grown 
Incub.  3  20  C.  2  2  days 
Lab.  24  days 
Artif.  yellow 
Yellow 
2.47 
2.065 
.76 
.64 
Yellow  Plum  
Yellow  Plum  
Ripe 
Half  grown 
0 
0 
Yellow 
Green 
2.12 
1.92 
.65 
•  59 
Half  grown 
Half  grown 
Incub.32°C.20days 
Lab.  24  days 
Artif.  yellow 
Yellow 
1.60 
1.395 
.49 
•43 
*  All  fruits  designated  "red,"  "yellow,"  and  "artificial  yellow"  were,  at  the  same  time,  ripe. 
The  results  above  reported  may  not  yet  be  as  extensive  as  might 
be  desired  in  order  to  follow  closely  the  changes  in  acidity  under 
different  conditions,  but  they  consistently  point  out  certain  relations 
of  interest,  which  may  be  briefly  enumerated  as  follows:  (1)  A 
comparison  of  the  acid  content  of  green  and  normally  ripened  fruits 
was  made,  using  Dwarf  Stone,  Sparks's  Earliana,  and  Yellow  Plum, 
all  direct  from  the  field.  There  were  no  marked  differences  between 
the  green  and  ripe  stages  within  the  variety ;  yet  the  acidity  of  the 
green  fruits  of  the  red  varieties  in  these  tests  is  somewhat  higher, 
while  the  acid  content  of  the  green  fruits  of  the  one  yellow  variety 
tested  is  somewhat  lower.  (2)  Fruits  of  Dwarf  Stone,  Truckers' 
Favorite,  Red  Peach,  Yellow  Peach,  and  Yellow  Pear  which  were 
picked  green  and  ripened  in  the  incubator  at  32-330  C.  (10-22  days) 
exhibit  a  higher  acid  content  than  either  those  ripened  on  the  vines 
