The check was carried out using diagrams by A.K. Boldyrev. The check was carried out as follows (see article). It turned out that the discrepancies did not exceed 1/2°; in some cases, with very small ∆g and ∆р, the reading accuracy dropped to 1°, but the latter is rare. Upon inspection, large discrepancies were discovered between the values of 2 V given by Larsen and 2 V obtained from the diagrams (see article). The total of 380 minerals were tested.