D. I. Mendeleev’ Periodic law was discovered in 1869, and in 2019 its 150th anniversary is celebrated worldwide. At the same time, the chemist created a table in the form “The experience of a system of elements based on their atomic mass and chemical similarity”, in which he arranged the chemical elements according to their atomic weights, after which he discovered an important pattern - at certain intervals of elements, their properties were periodically repeated. In 1870, D. I. Mendeleev prepared a new version of the table in which chemical elements were lined up vertically, forming groups, and six periods horizontally. This version of the table is more familiar to us, we are familiar with it from school. In 1876, the St. Petersburg publisher K.-E. Pratz was ordered a demo version of the Periodic Table, about which the historical source is preserved in the funds of the Central State Historical Archive of St. Petersburg. This article was written in order to restore historical justice, in particular, in order to confirm the primacy of the demonstration Periodic Table D. I. Mendeleev 1876 compared with the table of chemical elements in 1885, created on the recommendation of D. I. Mendeleev and located at the Scottish University of St. Andrews, who is currently challenging the Russian championship.