Imitation of ivory in two ways. Processing and dyeing of ivory and horn products DIY artificial ivory
Here are some ways to imitate ivory.
According to this method, 8 wt. hours of bleached white shellac are dissolved in 32 wt. hours of ammonia (sp. w. 0.995, which corresponds to 14% content of ammonia gas). The dissolution of shellac is carried out at a temperature of 35 to 40 ° with constant shaking in a closed vessel. After 5 hours, the solution is usually ready and is a syrup-like liquid. When shellac is completely dissolved, 40 wt. including zinc oxide (zinc white). The mixture must be well mixed to obtain a completely homogeneous mass. Mixing for a more perfect softening can also be done in a paint grinder.
Next, you need to remove ammonia from the mixture, which has already served its purpose. This is done by heating the mass. The mixture is then dried in air on glass sheets. After drying, the mass can be molded. To obtain a product of higher quality, the dried mass is ground into powder in a completely dry mill and the crushed mass is pressed. The pressure in the molds is usually maintained at about 160 kg per 1 cm 2 at a temperature of 125-128°. If you want to get objects painted in different tones, then dyes are added either to zinc white, or when grinding the dry mass.
Depending on the desired shade, add the appropriate amount of coloring matter.
The preparation method is as follows: prepare the following solutions beforehand:
Adhesive solution
Allow to swell 100 g good quality light glue in 1 liter of clean well water, dissolve with low heat and filter through the canvas.
Cellulose blend
50 g of well-bleached pulp (wood pulp - cellulose board - paper pulp) is kneaded with 3.5 liters of water until a homogeneous fibrous porridge is obtained.
alum solution
Dissolve 50 g of alum in 1 liter of hot water. The solution must be lukewarm, as if it is cooled too much, alum crystals may precipitate.
In a large pottery, 75% of the adhesive solution and 200 g of the cellulose mixture are mixed with the addition of 200 g of clean well water. To the resulting mixture is added 250 g of the purest possible, previously sifted through a sieve of alabaster gypsum. The mixture is thoroughly mixed until the gypsum is completely quenched and a homogeneous mixture is obtained. Then 200 g of alum solution is poured and again everything is well mixed.
The mass obtained in this way is poured into open molds, previously lightly lubricated with some kind of oil. In order for the mass to be evenly distributed, and there were no air bubbles, the mold must be shaken, after which it is left alone until the mass begins to thicken. At this moment, a piece of linen cloth is placed on the mold, and then a wooden or metal plate is placed on the cloth of the appropriate size. This plate serves as a lid for the mold. Next, they are pressed under pressure. The pressure-separated water drains fairly clean. The addition of alum gives the mass the ability to quickly harden and, in addition, holds back the glue in the mass so that only pure water. After pressing, the mold is left to stand for at least 15 minutes, after which the molded object is knocked out with a wooden mallet.
The molded objects are placed for a short time in hot water to wash off the fat that stuck from the oiled molds. Then the molded objects are dried in drying ovens and finally placed in a hot solution composed of different parts wax and stearin. Objects soaked through with this solution are cooled and brushed with a soft brush with gypsum powder until a sufficient ivory sheen is obtained. To give ivory a more yellow hue, glue, alum and cellulose are taken in slightly different proportions.
Dissolve 200 g of casein and 50 g of ammonia in 400 g of water (also use a solution of albumin in 400 g of water). To the solution is added a mixture of: Quicklime 240 g Acetic aluminum salt 150 g alum 50 g calcium sulphate salt 1200 g Oils (drying) 100 g (oil should be added to the mixture last) For dark objects, tannin from 75 to 100 g is taken instead of acetic aluminum salt. These compositions should be mixed well to form a uniform paste, which is rolled and thus plates of the desired thickness are obtained. These plates are either dried and stamped in metal molds that are preheated, or they are pounded into a very fine powder, which is then poured into molds and subjected to strong compression.
When the items are made, they are immersed in a bath consisting of: Water 100 wt. h. white glue 6 wt. h. Phosphoric acid 10 wt. h. Then they are dried, polished and varnished with shellac.
Imitation glue paste ivory
Billiard balls. Soak during the day 80 wt. hours of carpentry (bone) glue and 10 wt. hours of Cologne glue in 120 wt. hours of water. Then heated in a water bath until the glue dissolves and lumps disappear, after which a mixture of 5 wt. hours of powdered heavy spar and 4 wt. h. chalk. Mix thoroughly and add 1 wt. hours of boiled linseed oil.
Preparation of billiard balls from this mass is as follows. A wooden ball of appropriate size is immersed in the mass for a while, then the adhesive layer adhering to the ball is dried, then again immersed in the mass, dried, etc., until the ball is 1/5 larger than it should be in the future. Next, the ball is left to dry for at least 3 months, then it is turned and immersed for an hour in a solution of aluminum acetate salt. A solution of acetic aluminum salt can be obtained by mixing solutions of acetic lead salt (lead sugar) and a solution of aluminum sulphide salt (aluminum sulphate). In this case, a precipitate of lead sulphide salt precipitates. The filtered solution will be the aluminum acetate solution. After immersion in the solution, the ball is dried again. Then it is sanded again and left for 1 hour in a formaldehyde solution, then dried again and finally polished, as is practiced with real ivory.
Physicians from Imperial College London claim that they have managed to produce a bone material that is most similar in composition to real bones and has a minimal chance of rejection. New artificial bone materials actually consist of three chemical compounds at once, which simulate the work of real bone tissue cells.
Doctors and specialists in prosthetics around the world are now developing new materials that could serve as a complete replacement for bone tissue in the human body.
However, to date, scientists have created only bone-like materials, which have not yet been transplanted instead of real bones, albeit broken ones. The main problem of such pseudo-bone materials is that the body does not recognize them as "native" bone tissues and does not take root to them. As a result, large-scale rejection processes may begin in the body of a patient with transplanted bones, which, in the worst case scenario, may even lead to a large-scale failure in immune system and death of the patient.
Brain prostheses.
Brain prostheses are a very difficult, but doable task. Already today it is possible to implement human brain a special chip that will be responsible for short-term memory and spatial sensations. Such a chip will become an indispensable element for individuals suffering from neurodegenerative diseases. Brain prostheses are still being tested, but research results show that humanity has every chance of replacing parts of the brain in the future.
artificial hands.
Artificial hands in the 19th century were divided into "working hands" and "cosmetic hands", or luxury items.
For a bricklayer or laborer, they were limited to imposing on the forearm or shoulder a bandage made of a leather sleeve with fittings, to which a tool corresponding to the worker's profession was attached - pliers, a ring, a hook, etc.
Cosmetic artificial hands, depending on occupation, lifestyle, degree of education and other conditions, were more or less complex. The artificial hand could be in the form of a natural one, wearing an elegant kid glove, capable of producing fine work; write and even shuffle cards (like the famous hand of General Davydov).
If the amputation did not reach the elbow joint, then with the help of an artificial arm it was possible to return the function of the upper limb; but if the upper arm was amputated, then the work of the hand was possible only through the medium of voluminous, very complex and demanding apparatuses.
In addition to the latter, the artificial upper limbs consisted of two leather or metal sleeves for the upper arm and forearm, which were movably hinged above the elbow joint by means of metal splints. The hand was made of light wood and either fixed to the forearm or movable. There were springs in the joints of each finger; intestinal strings go from the ends of the fingers, which were connected behind the wrist joint and continued in the form of two stronger laces, and one, having passed along the rollers through the elbow joint, was attached to the spring on the upper shoulder, while the other, also moving on the block, freely ended with an eye. If you want to keep your fingers clenched with an extended shoulder, then this eyelet is hung on a button on the upper shoulder. With voluntary flexion of the elbow joint, the fingers closed in this apparatus and completely closed if the shoulder was bent at a right angle.
For orders artificial hands it was enough to indicate the measures of the length and volume of the stump, as well as of the healthy hand, and explain the technique of the purpose they were supposed to serve.
Prostheses for hands should have all the necessary properties, for example, the function of closing and opening the hand, holding and releasing anything from the hands, and the prosthesis should have a look that replicates the lost limb as closely as possible. There are active and passive prosthetic hands.
Passive only copy appearance hands, and active ones, which are divided into bioelectric and mechanical, perform much more functions. The mechanical hand replicates a real hand quite accurately, so that any amputee can relax among people, and can also pick up an object and release it. The bandage, which is attached to the shoulder girdle, sets the brush in motion.
The bioelectric prosthesis works thanks to electrodes that read the current generated by the muscles during contraction, the signal is transmitted to the microprocessor and the prosthesis moves.
Artificial legs.
For a person with physical damage to the lower extremities, of course, high-quality leg prostheses are important.
It will depend on the level of limb amputation right choice a prosthesis that will replace and even restore many of the functions that were characteristic of the limb.
There are prostheses for people both young and old, as well as for children, athletes, and those who, despite amputation, lead an equally active life. A high-class prosthesis consists of a foot system, knee joints, adapters made of high-class material and increased strength. Usually, when choosing a prosthesis, the closest attention is paid to future physical exercise patient and their body weight.
With the help of a high-quality prosthesis, a person will be able to live as before, with little or no inconvenience, and even carry out repairs in the house, purchase roofing materials and do other types of strength work.
Most often, all individual parts of the prosthesis are made from the most durable materials, for example, titanium or alloy steel.
If a person weighs up to 75 kg, then lighter prostheses from other alloys are selected for him. There are small modules specially designed for children from 2 to 12 years old. For many people with amputations, the emergence of prosthetic and orthopedic companies that make custom-made prostheses for arms and legs, make corsets, insoles, and orthopedic devices has become a real salvation.
To share with friends: Do elephants live in the wild today? Unfortunately no. Such is the paradox of the second half of the 20th century. These giants live only in nature reserves. Almost like Indians on American reservations. But even on the copses and lawns graciously reserved for them, there is no rest for large animals. Poachers from sniper rifles they are killed with explosive bullets in order to obtain and sell tusks on the black market. Everything else rots in the open air. Ivory among jewelers is still highly valued. And now they take the life of a huge creature for the sake of small trinkets.Killing elephants and simple, so to speak, Africans, like thousands of years ago. Negroes want to eat too. But the loss of animals from honest hunting for meat cannot be compared with killing them for profit. After all, the world retains a fashion not only for crafts made from tusks, but also ... for such exotic “trophies” as paper baskets made from the skin of the dried legs of the giants of the African fauna.
There have long been noble attempts to replace cane heads and ivory beads with plastics. Alas, these measures were not crowned with success. For example, the British flatly abandoned billiard balls made of synthetic resins. The Americans turned their backs on proposals to replace the white plates for the keys on concert grand pianos with the modification of fluoroplastic. And in Africa itself, fashionistas quickly learned to distinguish true bone from cheap polymer alloys.
Perhaps a Brazilian jungle tree called "macrocarnia" will save African elephants from being completely beaten by ruthless poachers. The fruits of this tropical plant are arranged in a very peculiar way. The seeds under the hard shell are hidden not in the pulp, but in a thick whitish liquid. Under the influence of heat and light, this latex can harden, change color to cream and become like a piece of ivory. After polishing, excellent imitation can be achieved. Brazilians have long been making beads from pieces of latex. True, the balls here are lighter than those made of ivory, but the addition of chalk corrects such a dissonance.
Japan is one of the countries that consume huge amounts of ivory: up to 130 tons per year. Ornaments in the oriental spirit, balls for rosaries and necklaces, accessories for the national tea ceremony are made from tusks. But the bulk of the African product goes to the factories of pianos and other musical instruments.
Japan has long supported many of the international programs to save wildlife from total destruction. economic activity person. Not so long ago, she announced that she was drastically reducing official imports of tusks and began to consider black market transactions a crime against nature. The government then hinted that it would soon impose a complete ban on this exotic raw material. Government officials began to talk seriously about the fact that the planet should not be deprived of wildlife.
Of course, this will be a blow to the appetites of poachers and their criminal income. But at the same time, Japanese industrialists were also worried. How to survive with such an onslaught of environmentalists?
The transition to plastic clearly did not suit. It is short-lived, does not differ in the necessary hygroscopicity and is not always durable.
The Japanese would not be Japanese if they had not immediately turned to their chemists with an order - masters of all sorts of ingenious inventions. The ivory substitute was urgently needed. At the same time, only benevolent. The director of the Tokyo chemical laboratory, Professor Mitsuri Sakai, a world-famous scientist, promptly responded. He expressed his willingness to help both ecologists and industrialists, for he understood contemporary issues protection of nature. Moreover, he expressed confidence that the Land of the Rising Sun will be able to supply a substitute for export to narrow the boundaries of black ivory markets around the world. The eminent professor said that Africa will not be left without elephants.
The Ministry of Industry immediately allocated the necessary appropriations. This specialist could be trusted, because he was known as a major dock in unexpected chemical technologies.
At first, Mitsuri Sakai looked for a new polymer substitute, but refused, not finding a promising one in terms of friction coefficients and dielectric properties. He then tried to create a synthetic resin material filled with fine powder from elephant tibia. But this combination did not work either.
And here is an artificial Ivory, which not every expert will distinguish from the real one in color, specific gravity, mechanical strength and other parameters of the tusks. The success was based on the fact that almost all the ingredients were natural. And this composition was really unexpected. For example, main part It's an eggshell and some protein. This is followed by casein extracted from cottage cheese. Three enzymes are added to it to decompose milk fats. Titanium oxide is then added to this "vinaigrette" to control color and specific gravity. It remains only to subject the mixture to cold sintering and holding in a thermostat. The tusk substitute is ready!
The chemical company Fukuwi immediately took up the production of the first batch, ordering shells from several restaurants at once. Having done approximately cubic meter substitute, it was immediately tested on a jazz piano as keys. The dashing musician responded with restraint, for he did not notice the difference. Q.E.D!
Why is this circumstance so important? Yes, because the virtuoso's fingers slide over the polymer keys, the game becomes uncomfortable.
Firm "Fukuwi" believes that the new material is suitable for jewelry, and for boxes for expensive perfumes, and mouthpieces for wind instruments. But Professor Nobiuki Yokoyama proved that the ivory substitute is suitable for dentures in terms of its chemical and physical properties.
Real bone carving is a very expensive art form that takes a long time to learn. Therefore, you can often see all kinds of imitations of bone carving. Today I want to show two of my simulation options, which I came up with recently:
Wood putty;
Silicone molds, a vial for pasta, a rag or napkins and a good mood!
modeling gel "TAIR" or paste Sonnet.
Getting started with this panel, I already had little experience in creating an imitation of smooth and embossed bone carving. Therefore, I decided to try to imitate the third type of thread - through. I reviewed a lot of images, read about this direction and realized that a through thread can be used not only as an independent “wall”, it can also be leaned against the base.
Having chosen the silicone mold I liked according to the openwork pattern, I filled it with Sonnet paste and left it overnight. It is not necessary to fill in Sonnet, you can use modeling gel or TAIR diluent paste. Before that, I have already cast openwork lace from Tair modeling gel many times, I really like the durable and flexible result. The resulting castings can be cut, painted, varnished, wound on any even a round surface. Such materials must be poured and left in a silicone mold for several hours.
So, we have two castings, the production of which took a day. Let's get to work.
The first step is to sand the workpiece, especially at the ends.
Next, let's make a frame of harnesses. We tear off a small piece of clay, knead it and put it in mold. Cut off the excess with a sharp wallpaper knife. There is no need to wait for the clay in the mold to dry. Carefully take out and immediately glue the mold obtained from their clay onto the PVA glue. Slightly and gently press the flagella to the workpiece with your fingers. After a while they will stick and we will leave them to dry. Clay dries for a long time. It is not necessary to dry it with a hair dryer, it can crack.
In order not to waste time, we apply openwork to the workpiece, make marks on the upper arch and cut off the excess with scissors. We try on, if everything suits, we lubricate the workpiece with glue and glue openwork castings. You don't need to do anything to fix them.
I wanted this panel to be some kind of architectural element, so I looked at my castings and found a molded mascaron mold that was once ready for testing. It was a test casting from the Sonnet paste, the result of which I was not satisfied with. The cast form dried for a very long time (2-3 days), shrunk and the face of the mascaron itself was damaged. Therefore, I no longer use this paste for deep castings, it is only suitable for shallow forms. But since, according to my idea, the panel was made in the architectural style, it was this not the most successful casting that came in handy for me. It already had a trace of time on it.
But after trying it on the workpiece, I realized that it was too small and lost, so I took another mod with the image of a bas-relief and made a mold out of it with clay, which I glued onto the workpiece with glue, and laid and glued a mascaron on top of it. By the same principle, I made and glued a garland of clay.
Now all the finished elements need to be dried properly, about 8 hours
We cover the entire product from all sides with the paint "Acrylic-Hobby De Luxe" Ivory. Dry, again apply two or three layers of varnish.
When all the elements are dry, we proceed to create the effect of a carved bone. To do this, dilute brown paint with water and begin to fill in all the recesses. Do not forget to also coat the entire surface to give the desired shade. Carefully remove excess with a cloth or napkin. After thorough drying, we close everything with a finishing semi-gloss varnish, dry it and admire the finished result!
If you want the end result to be completely new, carefully watch the details on the casts and castings. I wanted the mascaron, garland, and rope frame to look old-fashioned, beaten by life, as they are protruding architectural elements. Therefore, I did not need much accuracy for this work. And, relatively speaking, the damaged nose went into a plus, not a minus. But perfect for new job, after all, it is necessary to monitor the quality of the cast or casting and it is advisable to put one layer, no more, of glossy varnish on the most voluminous elements.
I hope you liked my version of imitation of through bone carving and you can try it in your work without any problems!
ARTIFICIAL BONE
Susan Liao and her colleagues at the National University of Singapore (NUS) have created artificial bone from an inorganic material with a nanostructure similar to natural bone.
Human bones consist mainly of nanocrystals of hydroxyapatite (65%) and collagen (25%) (and there are also springs). In dentin, this proportion is slightly different - 70% and 20%.
The scientists decided to make artificial bone from mineralized collagen, a biocompatible material that could be an excellent base for implants and prostheses. At the same time, they developed a method for the production of nanocomposites with different concentrations of collagen and carbonates that make up the bone (they designated this material as nCHAC).
Researchers were especially interested in the question of what would happen when the proportions of the ingredients changed. It turned out that by manipulating the initial solutions and, accordingly, the concentrations of carbonates and collagen, it is possible to create nanocomposites with different morphologies. In particular, with nCHAC crystals of different sizes and shapes. They formed needles, gradually shortening and forming spherical particles. It was similar to the formation of a real bone, the authors of the experiments say.
And because of the different structure, they also changed mechanical properties bones. In this way, new method can help create artificial biomaterials designed for a variety of working conditions in the body and for prosthetics of various bones, the researchers believe.
So far, the structure of the obtained bone is not quite identical to the natural one, but in the future, Liao intends to reproduce using her method the same nanofibers that are observed in real bones.
Homologous bone bank of bone grafts
Artificial bone Orthoss. Autogenous (endogenous) bone or homologous bone (from a bone graft bank) is often used for bone grafting in traumatology and orthopedics. However, the use of autogenous bone is limited due to its difficult accessibility and traumatization of the patient during additional surgery. Homologous bone carries with it high immunological risks and the risk of infection (AIDS, hepatitis, etc.). Artificial bone substitute, such as hydroxyapatite, differs from natural bone in structure and composition, which makes it extremely difficult for it to participate in the process of natural osteogenesis. With the advent of Orthoss, an alternative bone grafting material is available that preserves the natural inorganic structure of the bone. Orthoss is easily integrated into the natural process of bone formation through osteoblasts and osteoclasts. Orthoss is composed of substances that make up the inorganic matrix of the bone, while maintaining the properties of the natural inorganic structure of the bone. Due to its natural composition, Orthoss has a high degree of resemblance to human bone.Porous structure - like natural bone
The pore size plays a decisive role in the bone integration of the implant. Orthoss has a natural pore system that promotes bone regeneration through blood vessel sprouting and bone cell migration. The pore size varies due to its natural origin and is in the order of 100 µm.
Inner surface similar to natural bone
Due to the intensively developed volumetric network structure of the connecting pores, the inner surface area of the material is more than 90 m2/g and inner space Orthoss closely corresponds to the human cancellous bone. This provides a large area of contact between the implant material and the newly formed bone.
Crystal structure - like natural bone
The inorganic basis of a human bone represents the smallest crystals of apatite. During the unique technological process production in Orthoss retains a crystalline structure similar to human bone. This facilitates the integration of Orthoss into the natural process of bone regeneration.
Chemical composition - like natural bone
Compared with synthetic materials in Orthoss biological apatite has fewer hydroxyl groups and more carbonate ions. The ratio between calcium and phosphate ions is 2:1, which is fully consistent with the human bone.
Artificial bone is able to pass into ligaments
Using skin cells, tissue engineers at the Georgia Institute of Technology have created artificial bone that can, like natural bone tissue, transition into other types of tissue, such as ligaments and tendons. The resulting tissue showed a gradual transition from bone to softer tissue, rather than the sharp jump in density that is characteristic of the previously described artificial bone samples. This will ensure better integration of the new bone tissue into the body and better distribution of the load within such tissue. The study was published in one of the August issues of the journal Proceedings of the National Academy of Sciences.A team of researchers led by Professor Andres Garcia of the George W. Woodruff School of Mechanical Engineering at the Georgia Institute of Technology has not only been able to create artificial bone that transitions into softer tissue, but has also been able to transfer the technology in vivo in a matter of weeks.
Scientists managed to create such a tissue using a three-dimensional polymer scaffold, at one end of which a high concentration of the transcription factor Runx2 was maintained, and towards the other end, the content of the transcription factor gradually disappeared, i.e. the researchers created a precisely calculated spatial gradient of this factor. Then the entire framework was evenly populated with skin fibroblasts. As a result, fibroblasts that got into the part of the scaffold containing a large amount of the Runx2 factor became bone tissue, and those that populated its opposite end, devoid of this factor, became ligaments and tendons.
If the proposed technology passes the necessary tests, one of its applications will be operations on the anterior cruciate ligament (anterior cruciate ligament (ACL)). The fact is that at present, surgical treatment of ACL injuries is not very effective, since it is impossible to reproduce the transition from bone tissue to the tissue of the ligament itself.
According to the researchers, every organ in our body has a complex, heterogeneous structure. Therefore, the ability to artificially create tissues, the best way replicating the properties of nature is a huge leap forward for tissue engineering.
Who is a bone? Information about bones
Bone is a solid (bearing) component of the endoskeleton of a living organism. The composition of bones includes both organic and inorganic substances; the number of the former is greater, the younger the organism; in this regard, the bones of young animals are flexible and soft, while the bones of old ones are hard and brittle. The relation between the two constituents represents the difference in different groups of vertebrates; thus, in the bones of fish, and especially in deep-sea fish, the content of mineral substances is relatively low, and they are distinguished by a soft fibrous structure.Mineral constituents
In an adult, the amount of mineral constituents (mainly calcium phosphate and carbonate and magnesium phosphate, as well as fluoride, calcium chloride, etc.) is about 60-70% of the bone weight, and organic matter(mainly ossein) - 30-40%. Bones have great strength and tremendous resistance to compression, resist destruction for an extremely long time and are among the most common remains of fossil animals. When calcined, the bone loses organic matter, but retains its shape and structure; by exposing the bone to the action of an acid (eg hydrochloric acid), minerals can be dissolved and a flexible cartilaginous skeleton of the bone can be obtained.
The shape of the bones are divided into long, wide and short. Long or tubular bones - those in which the length strongly predominates over the width and thickness; they have a more or less cylindrical middle part, a body (Corpus s. Diaphysis) with a cavity inside and 2 ends or epiphyses (Extremitates s. Epiphyses), which are always wider than the body and covered on the articular surfaces with a layer of cartilage, located in the limbs and more or less curved. In broad bones, two dimensions predominate over the third; such bones serve primarily to form the walls of cavities containing various organs (skull, chest, pelvic cavity) and can be flat, curved, concave, etc. In short bones, no single dimension predominates significantly over others; these bones are irregular, rounded or polyhedral (eg vertebrae, wrist and heel bones).
The surface of the bone can represent various depressions (striations, pits, etc.) and elevations (corners, edges, ribs, ridges, tubercles, etc.). Irregularities serve to connect bones to each other or to attach muscles and are the more developed, the more developed the muscles. On the surface are the so-called "nutritional holes" (Foramina nutritiva), through which the feeding and blood vessels enter the bones.
Bones are divided into dense and spongy bone. The first is homogeneous, hard and makes up the outer layer of the bone; it is especially developed in the middle part of the tubular bones and becomes thinner towards the ends; in broad bones it is 2 plates separated by a layer of spongy substance; in short ones, in the form of a thin film, it dresses the bone from the outside. The spongy substance consists of plates intersecting in various directions, forming a system of cavities and holes, which merge into a large cavity in the middle of the long bones.
Chemical industry Chemical news stories
Find out in more detail the news in the field of chemistry, interesting chemical elements, how the periodic system of elements is changing, what awaits it in the near future?. Notes of scientists and specialists - useful articles and materials about chemistryThe outer surface of the bone is dressed in the so-called periosteum (Periosteum), a connective tissue sheath containing blood vessels and special cellular elements and serving to nourish, grow and restore the bone. The internal cavities of the bone are made with a special soft cloth called bone marrow.
