CHEMICAL INVESTIGATIONS.
Reading edition
EXCESS OF TANNIN IN DISEASED WOOD.
The principal features of the chemical investigations which have been continued in charge of Mr. Joseph Shrawder, are as follows:
The abnormal tannin content of infected material was the chief subject of interest in the last report. Invariably, infected wood and hypertrophied material continue to show a higher tannin content than sound material from the same sample.
LOSS OF VOLATILE MATTER.
Moisture and other volatile matter proved of interest also. By prolonged heating at temperatures up to 155°C, infected material showed a greater ratio of loss.
CELLULOSE DETERMINATIONS.
A series of cellulose determinations was also made to note the effect of the fungus on wood and bark. A higher percentage of cellulose in sound material leads us to believe that it is being digested with the formation of acids and other soluble matter. It may also be that part of this soluble matter is reported as tannin by the hide powder method. This, with the deficiency of cellulose, may account for the relative high tannin content appearing on analysis.
CHEMICAL CHANGES.
The determination of starch, reducing sugar, and nitrogen shows that decided chemical changes are being produced by the fungus. However, this work was not brought to a satisfactory conclusion owing to the sudden termination of the work of the Commission.
NEW INJECTION MATERIAL FOR TREE MEDICATION.
Some preliminary work was also started in a search for a suitable injection material to be used in the tree medication experiments. It is evident from the chemical investigation that a suitable injection material must not coagulate the excessive tannin and other colloids in the wood and bark, and that it must be able to penetrate cutin in suberin in order to diffuse properly through the infected area. A brief investigation of a modified chlorine solution showed that it fulfilled these requirements in many respects, but its value in treating trees has not been determined.