At the beginning of this century, E. S. Fedorov created a method for determining a substance by the shape of its crystals, which he called “Crystal-chemical analysis” (29). This method, based on measuring the angles between the outer faces of crystals, was an important fundamental and practical achievement of crystallography. Over the next few years, this method, which in its essence is best called goniometric diagnosis, was significantly simplified by Fedorov’s school. Currently, the Fedorov Institute and the Central Geological Prospecting Institute (TsNIGRI) are compiling a “Crystal Determinant” (2), which will enable goniometric diagnosis in its new version to enter, along with optical diagnosis, into the daily practice of a crystallographer, chemist, and mineralogist. The main advantages of goniometric diagnosis are the complete absence of substance consumption, comparative speed of determination and the same degree of simplicity of diagnosis both in the case of simple and in the case of extremely complex substances. The main disadvantages of the goniometric method are the need to have the substance in the form of crystals and the variability of the external shape of crystals of the same substance. The second drawback may in some cases make it impossible to determine the substance by goniometric method. This drawback is especially noticeable in Barker’s version (16) of the goniometric diagnosis (20, 328, 329), to a somewhat lesser extent in Fedorov’s “Crystallographic Analysis” and to an even lesser extent in the version embodied in the “Identifier of Crystals” mentioned higher.
As we know, the X-ray method can be used in mineralogy (and in all branches of science and technology that rely on it) to solve a number of problems. The objectives of our research are to answer a number of the following questions. The answers to these questions should shed light on the nature of the substance of various coals, they can provide a new way for an accurate quantitative method of distinguishing coals from each other, one can expect that this method of distinguishing coals will help the geological parallelization of individual coal seams. In the future when linking X-ray properties with chemical ones with the help of analyzes and determinations of the thermal properties of coal, it becomes possible to learn from X-ray photographs of coal to judge, at least to some extent, about its qualities as a fuel. We have specified our immediate work as follows: to take Debye patterns of a successive series of minerals: graphite, shungite, anthracite and coal and discuss the results obtained.
The classification of 32 types (or groups) of crystal symmetry, i.e., the basis for dividing them into systems, or systems, can be based on various principles. Of these principles, the following two are the main and most natural. It is possible to classify the types (or groups) of symmetry, i.e., certain spatial collections of symmetry elements as such, by themselves, without relation to the complexes of possible faces and edges of the crystal to which these types of symmetry are characteristic. Let us call such classifications “purely geometric”. It is possible to classify the types of symmetry, taking into account the properties of those complexes of possible faces and edges of the crystal, in other words, those spatial lattices to which these types (groups) of symmetry are characteristic. Let us call such classifications “crystallographic”. The proposed classification, nomenclature and symbolism are closely linked by a single principle and are entirely based on a genetic trait — on the generative elements of symmetry.
This article is a report on the experiments that I conducted during the period from May 23, 1916 to December 20, 1917. These works, like many others of their kind, were caused by the extreme shortage of chemical products on the Russian market due to the World War. We came to the decision to first address the issue of producing acetyl chloride using sulfur. This article represents a complete report on all the work carried out by the author in the direction indicated here.
Mapping mineral deposits is one of the most important objective methods for studying them. This work is devoted to the development of rational mapping methods, treating this issue in a general form. The first reason for this work was the urgent need for a rationally constructed map of the Altai polymetallic deposits. The need for such a map immediately became clear in the first years of research by the Geological Committee in Altai, and at the same time we both undertook work in two directions: a mapping methodology was developed and literary, archival and material unpublished by Altai workers of Geological Comittee an necessary for mapping the Altai deposits, was collected. The result of work in the first direction is this article.
We have two equal mutually tangent circles O1 O2. We have a straight line AB, tangent to both, and a new circle C, tangent to both data. We assert that the point of intersection of these two tangents, i.e. points D and E, as well as the point of tangency of two given circles, i.e. point F, are equally distant from point G, i.e. from one of the meeting points of the circle C and straight CF. Proof of Prof. E.S. Fedorov.
The named crystals were given to me for crystallographic study by Professor N.S. Kurnakov, who obtained them for the first time. The author carried out: goniometric studies, optical studies and studies of crystal isomorphism. See the article for results and pictures.
