In this paper, the differences in mechanical strength tested during the static tensile and compression test of Scots pine (Pinus sylvestris L.), European larch (Larix decidua) and Norway spruce (Picea abies) wood exposed to continuous soaking in water with a salinity of 7‰ were determined. The value of salinity corresponded to the average salinity on the Polish Baltic coast. This paper also aimed to examine the content of mineral compounds absorbed during four cycles of two weeks each. The essence of the statistical research was to identify the effect of the mineral range compounds and salts depending on the mechanical strength of the wood. Based on the results of the experiments, it can be concluded that the medium used has a specific effect on the wood species’ structure. The effects of soaking on the wood parameters depend obviously on the type of wood. A tensile strength test of pine, as well as the tensile strength other species, was enhanced by incubating it in seawater. A native sample’s initial mean tensile strength was 82.5 MPa, which increased to 94.8 MPa in the last cycle. It was found that the larch wood had the lowest tensile strength difference (9 MPa) of the woods studied in the current study. Four to six weeks of soaking was necessary to notice an increase in tensile strength.

The article describes the process of hot water extraction treatment of a specific material—in this case, shavings of hemp shives of different thicknesses, sorted by their thickness into three different fractions of 0–4 mm, 4–8 mm, and 8–12 mm. In addition, each sample from a given fraction was separately subjected to one, two, and three extraction processes. After the material was treated with extraction, cellulose determination was performed using the Kürschner–Hoffer method in order to find out the effect that hot water extraction had on the cellulose content of the test material. This research aims to determine whether hot water extraction strongly alters the cellulose content, which may translate into a change in efficiency when producing second-generation biofuel produced from this material. The cellulose determination showed the smallest cellulose losses were in chips 4–8 mm thick, while the largest were in chips 0–4 mm thick. Each repetition resulted in a loss of cellulose, with the steepest loss occurring after the second repetition of HWE, and the smallest after the third repetition—the exception being the 4–8 fraction, in which the smallest decrease occurred after the first repetition of the HWE (Hot Water Extraction) process.