木材粉の眞比重に就て
スポンサーリンク
概要
- 論文の詳細を見る
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.木材の比重は普通容積比重を以て現される。その値は普通零點以下であつて甚廣範圍に亙つて居る。その因つて來るところ, 主として木材組織の空隙容積の大小にある。然るに木材よりその含有水分及び空隙を全く去り木材の實質部分のみを考ふるときその比重は從來の測定結果によれば樹種の如何に不拘略一定であつて1.40-1.56とされて居る。尤も極めて樹脂を含むこと多き樹種及び特に硬き心材を有する樹種には多少の例外がある。これ迄の測定方法は何れも空氣中に於ける試料の秤量値より計算され表ものである。然るに木材粉はその表面竝に間隙に多くの水分及び瓦斯體を含む許りでなく木材を構成する結晶内部に浸入して所謂ミセル内膨潤をなすものあることも想像さるるところである。たとへ絶對乾燥を行へる試料と雖も空氣中に於て秤量を行ふ限りその過程に於て空氣その廻の瓦斯體の吸着を免るるものではない。その影響は比重の測定に際して必ずしも無視し得ないことはこの測定結果の示す通りである。絶對乾燥を行つた木材粉を水中に投ずるときその一部分は水面に浮んで長時間沈まる事實の原因の一つは上に述べたことによつて説明されると思ふ。そこで空氣中に於ける瓦斯體の吸着を防いで比重を測つたならばどんな値が得られうかといふことが我々の問題である。
- 九州帝國大學農學部の論文
九州帝國大學農學部 | 論文
- 日本産 Rhus 屬樹種の果實に於ける蝋の含有量並に收量に關する組織の定量的研究
- 土壌の各層に於ける肥料の分布と胡瓜及び茄子の成育
- 攀纒植物の機巧に就いて
- 航空機用木材の物理的性質(第一報)
- 日本産重要木材の摩擦係數