The article "Determination of the Size and Internal Structure of Colloid Particles by X-rays" by P. Scherrer, published in 1918, discusses the use of X-ray diffraction to determine the size and internal structure of colloid particles. Scherrer notes that the internal structure of colloidal particles is not well understood, so studying them using X-ray diffraction is of interest. Two possible cases are considered: (1) colloidal particles with crystalline structure, which would produce characteristic diffraction patterns, and (2) colloidal particles without crystalline structure, which would show only weak diffraction peaks. The theory suggests that the positions of diffraction peaks depend only on the crystal lattice structure, while the width of the peaks is related to the size of the crystalline particles. The formula for the half-width of a diffraction peak is derived, which allows the determination of particle size. Experimental results show that colloidal gold and silver particles are small crystalline particles with the same crystal lattice as macroscopic gold crystals. The results also indicate that aged silica and tin gel particles show strong crystalline diffraction patterns, suggesting they are on the verge of crystallization. Organic colloids like proteins, gelatin, casein, and cellulose show amorphous structures, suggesting they may be single molecules or disordered aggregates. The study provides a new method for determining particle size and confirms the crystalline nature of some colloidal particles. The findings are significant for understanding the structure of colloidal particles and their potential for crystallization.The article "Determination of the Size and Internal Structure of Colloid Particles by X-rays" by P. Scherrer, published in 1918, discusses the use of X-ray diffraction to determine the size and internal structure of colloid particles. Scherrer notes that the internal structure of colloidal particles is not well understood, so studying them using X-ray diffraction is of interest. Two possible cases are considered: (1) colloidal particles with crystalline structure, which would produce characteristic diffraction patterns, and (2) colloidal particles without crystalline structure, which would show only weak diffraction peaks. The theory suggests that the positions of diffraction peaks depend only on the crystal lattice structure, while the width of the peaks is related to the size of the crystalline particles. The formula for the half-width of a diffraction peak is derived, which allows the determination of particle size. Experimental results show that colloidal gold and silver particles are small crystalline particles with the same crystal lattice as macroscopic gold crystals. The results also indicate that aged silica and tin gel particles show strong crystalline diffraction patterns, suggesting they are on the verge of crystallization. Organic colloids like proteins, gelatin, casein, and cellulose show amorphous structures, suggesting they may be single molecules or disordered aggregates. The study provides a new method for determining particle size and confirms the crystalline nature of some colloidal particles. The findings are significant for understanding the structure of colloidal particles and their potential for crystallization.