The density of the actual wood substance, i.e. the material comprises the wall of the fibers and other cells may be the same in all species. Its specific gravity has been determined to be 1.40 to 1.56. But the measurements were performed without considering the adsorption of air during the operation. Now the defect is excluded by the following method and obtained new density value of the wood substance. A certain quantity of the speciemen (in the powdered state), which had been dried, was weighed, and it was put into a glass tube which had been sealed at one end, as is shown by A in Fig. 1. A part of the tube was necked with a burner several centimeters from its sealed end as is shown by B in the figure. Then the tube was connected to an oil rotary pump which was capable of evacuating down to a pressure of about 0.01 mm of mercury. When the evacuation was ended the tube was sealed at its neck as shown in C, Fig. 1. The tube thus sealed was weighed, and then its volume was measured. Distilled water was then introduced into the tube by breaking the neck of the tube at b in distilled water in the way shown by D in Fig. 1. Next the weight of the specimen in distilled water was measured. After the weight in distilled water of the glass tube containing the specimen, and the broken neck, bbth of which were perfectly filled with water, had been measured, the glass tube was broken along the filed line a, and the specimen was taken out of the tube. Then the weight in distilled water of all the parts of the broken glass tube, as shown by E in Fig. 1, was measured in the same way, and the weight of the specimen only in distilled water was obtained immediately. Finally after all the parts of the broken glass tube had been well dried, their weight in air was measured. From the weight of the glass tube only and that of the sealed glass tube containing the specimen which was well evacuated, we can obtain immediately the net weight of the specimen. From tke net ' weight of the specimen and its weight in distilled water, the net density of the specimen was calculated. The results is tabulated in Table 1, an d the men value is calculated to be 1.60.
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