8 
CAROLINE RUMBOLD 
Measurement of Intake 
The intake of an injected tree was measured by weighing the jars con- 
taining the solutions. This was done with a small brass beam-balance which 
recorded the weight in grams. It was assumed that a cubic centimeter of the 
solution weighed a gram. It was thought that the amount of error caused 
by this assumption was so small as not to need to be calculated when esti- 
mating the amount of substance injected into a tree. Experiment showed 
that the amount of evaporation from the jars through the parchment cover- 
ing was so small that it could be ignored. This amount was found to average 
40 cc. per month. If the paper cap was torn the average evaporation was 
70 cc. per month. 
There was also evaporation of the more volatile substances in dilute 
solution. This could be noticed in the case of the cresols and phenols and 
of some of the ammonium solutions. The amount of this loss was not 
tested. The jars containing such solutions had their contents renewed 
frequently, and an attempt was made by reinjecting to keep the solutions 
going into the trees rapidly. These precautions were thought to be sufficient 
to make it unnecessary to calculate either the loss or the concentration of 
substance due to such evaporation in the experimental work so far at- 
tempted. 
Substances Injected 
The following substances weie injected into the trees: 
Inorganic Substances Organic Substances 
Copper sulphate Methyl alcohol 
Copper chloride Formalin 
Zinc carbonate Acetic acid 
Mercuric chloride Formic acid 
Potassium chromate Lactic acid 
Potassium bichromate Citric acid 
Barium chloride Aniline sulphate 
Colloidal cuprous hydroxide^ Phenol 
Colloidal metallic silver Sodium carbolate 
Colloidal metallic mercury Phenol Sodique^ 
Potassium carbonate Para nitro phenol • ^ 
Potassium hydroxide Ortho nitro phenol 
Potassium sulphate Picric acid 
Ammonium carbonate Meta cresol 
Ammonium chloride Para cresol 
Ammonium hydroxide Thymol 
Ammonium sulphate Pyrocatechin 
Sodium carbonate Pyrogallic acid 
^ I am indebted to H. K. Mulford Company of Philadelphia for these colloidal prepara- 
tions. The metals were protected in each case by a second colloid. 
^ A patent medicine made of carbolic acid and caustic soda. 
