The article, titled "Determination of the Size and Internal Structure of Colloidal Particles Using X-Rays," by P. Scherrer, was presented by P. Debye on July 26, 1918. The paper explores the inner structure of colloidal particles, which were previously unknown. Two scenarios are considered: (1) particles with a crystalline structure, and (2) particles without a crystalline structure. For particles with a crystalline structure, the expected X-ray干涉 (interference) patterns would be characteristic of the crystal lattice. The theory suggests that the position of these interferences is determined by the type of lattice, while the width of the interferences is related to the size of the individual crystals. This allows for the determination of the particle size through the measurement of the intensity profile of the interferences. For particles without a crystalline structure, only one or two very flat maxima near the incident X-ray beam are expected, making it difficult to determine the inner atomic arrangement. The experiments conducted supported these theoretical predictions. They confirmed that colloidal gold particles have a crystalline structure with the same lattice as macroscopic gold crystals. The formula for the angle-dependent half-width of the maximum was validated, and the particle sizes obtained matched those determined by other methods. Additionally, aged silica and tin sulfide gels showed intense crystalline interferences, indicating that they were in the process of crystallizing. Organic colloids like proteins, gelatin, casein, cellulose, and starch exhibited amorphous structures, suggesting that these particles might be individual molecules or arrangements of molecules without regular order. The findings provide valuable insights into the nature and structure of colloidal particles, contributing to the understanding of their fundamental properties.The article, titled "Determination of the Size and Internal Structure of Colloidal Particles Using X-Rays," by P. Scherrer, was presented by P. Debye on July 26, 1918. The paper explores the inner structure of colloidal particles, which were previously unknown. Two scenarios are considered: (1) particles with a crystalline structure, and (2) particles without a crystalline structure. For particles with a crystalline structure, the expected X-ray干涉 (interference) patterns would be characteristic of the crystal lattice. The theory suggests that the position of these interferences is determined by the type of lattice, while the width of the interferences is related to the size of the individual crystals. This allows for the determination of the particle size through the measurement of the intensity profile of the interferences. For particles without a crystalline structure, only one or two very flat maxima near the incident X-ray beam are expected, making it difficult to determine the inner atomic arrangement. The experiments conducted supported these theoretical predictions. They confirmed that colloidal gold particles have a crystalline structure with the same lattice as macroscopic gold crystals. The formula for the angle-dependent half-width of the maximum was validated, and the particle sizes obtained matched those determined by other methods. Additionally, aged silica and tin sulfide gels showed intense crystalline interferences, indicating that they were in the process of crystallizing. Organic colloids like proteins, gelatin, casein, cellulose, and starch exhibited amorphous structures, suggesting that these particles might be individual molecules or arrangements of molecules without regular order. The findings provide valuable insights into the nature and structure of colloidal particles, contributing to the understanding of their fundamental properties.