Testing minerals with a blowpipe has its own history. When searching for ores, Russian mining engineers constantly used this method, developing and improving it. The most basic test with a blowpipe consists of heating a mineral fragment in order to study its behavior at high temperatures. Fusibility is the most important feature in determining minerals. The existing scale of mineral fusibility is satisfactory. However, it is better to take the following minerals as standards for the scale: No. 2 - halite (800°), No. 3 - grossular, fluorite, albite (1100°), No. 4 - nepheline or muscovite (1200-1250°), No. 5 - orthoclase, microcline or talc (1300-1350°), No. 6 - beryl (1410°) or serpentine (1450°). Determination of melting point is possible with an accuracy of up to +20° if it is carried out on rods prepared from dough converted into mineral powder. In this case, rods from the pyroscopes of the State Porcelain Factory prepared in the same way should be taken as standards. The melting point of the pyroscope scale numbers is given in the table. Clarification of the melting point is especially important for silicates. The melting points of many minerals are given in the first volume of the Reference Tables of Physical Quantities of the Technical Encyclopedia (1935).
Considering various distributions of natural qualities and properties, mainly from the field of geological sciences, the author came to the idea of replacing one argument with another, functionally related to it. With such a replacement, the type of distribution function changes and, for example, symmetrical forms of distribution turn into asymmetrical ones and vice versa . The functional transformation of variables leads to the identification of families of distribution functions that reflect the same natural process in different forms. Among the forms, there may also be simpler ones, for example symmetrical ones, and finding them is advisable. The author poses a general problem: what should be the type of connection between mutually replaceable arguments so that the asymmetric monotonic form is reduced to the Gaussian function, and in such a way that some constants remain unchanged. The solution to this problem establishes that the form of the function is logarithmic. A particular form of this connection will have the expression 2 = lg(x - a) + c. The author deduces some properties of the logarithmic distribution and points out numerous cases (in geochemistry, petrology, geology, beneficiation, calculation of mineral reserves, distribution of matter during sedimentation, hydraulic classification, etc.) where asymmetric distributions can be transformed into Gaussian form by a logarithmic transformation.
