Sublimate

SUBLIMATE, mercuric chloride, HgCl₂, Hydrargyrum bichloratum corrosivum, has been known for a long time and is still obtained by Kunckel's method (1716). Mercuric sulfate, obtained by evaporating to dryness a solution of mercury in hot H₂SO₄, is mixed with NaCl and a small amount of manganese dioxide; upon heating in clay retorts on a sand bath, the reaction takes place: HgSO₄ + 2NaCl = HgCl₂ + Na₂SO₄; the reaction goes to completion, and sublimate sublimes into the cold parts of the retorts; this property of it served as the reason for naming mercuric chloride sublimate (from the Latin word sublimatum, sublimate). To obtain sublimate, one can also act with chlorine on mercury at ordinary or elevated temperatures. Sublimate is a heavy, white, crystalline powder, soluble in 16 parts of cold water, in 3 parts of boiling water, in 3 parts of alcohol, in 4 parts of ether. It boils at 302°, crystallizes in the form of white needles. In aqueous solution, it is unhydrolyzed and very slightly ionized. Sublimate easily gives complex compounds, for example, when dissolved in concentrated HCl, hydrogen chloromercurate, H"HgCl'₃ or H"₂HgCl₄; its salts are formed upon the action of metal chlorides on sublimate, for example, K₂HgCl₄ or Na₂HgCl₄; they are easily soluble in water. Numerous basic salts are known, formed by boiling an aqueous solution of sublimate with mercuric oxide,—bright yellow oxychloride, HgCl₂·2HgO, and black HgCl₂·Hg₂O. Aqueous and alcoholic solutions of sublimate are transparent, have a metallic taste, and have an acid reaction, which upon the addition of NaCl turns into a neutral one. The local action of mercury salts on cell protoplasm is caused by their specific relation to protein substances, with which they form albuminates (see Mercury). The comparative rapidity of absorption of sublimate can be related to the easy solubility of mercury albuminate in the presence of NaCl. Various organic substances, especially under the action of heat and light, reduce sublimate and convert it into calomel. Sublimate belongs to the most soluble and poisonous salts of mercury. Absorption of sublimate occurs in the intestine; sublimate is excreted through the intestinal mucosa and kidneys. The excretion of the organism occurs significantly slower than absorption. Locally, sublimate acts irritant and caustic. Due to the fact that NaCl is an integral part of all animal fluids, the easy absorption of mercury salts and the comparative frequency of sublimate poisoning in various methods of its application for therapeutic purposes become understandable. For the antiseptic use of sublimate, see Antisepsis and asepsis, antiseptic substances. Internally, sublimate is rarely prescribed due to its toxicity and irritating properties; it is given in doses of 0.001 and 0.005 in aqueous or alcoholic solutions simultaneously with protein substances (milk) and NaCl. It cannot be prescribed on an empty stomach. Sublimate is most often used as a disinfectant (see below). Washings of serous cavities and the uterus in the postpartum period with sublimate solutions are particularly dangerous. Acute poisoning can occur with the introduction of doses close to therapeutic ones. A dose of 0.1 can be fatal when introduced into the blood or applied to an open wound surface. Concentrated sublimate solutions, e.g., 1–3%, are used to destroy the epithelium in freckles and in pityriasis. For more energetic cauterization in syphilitic infiltrates and ulcerations, strong 10% solutions of sublimate in alcohol are sometimes used. When a sublimate solution is introduced into the blood of warm-blooded animals, irritation of the gastrointestinal tract is observed, expressed by salivation and vomiting, severe, often bloody diarrhea with tenesmus. Respiration first quickens, then becomes shallow. Heart activity weakens. Death occurs with phenomena of paralysis of the heart and respiratory center. The same phenomena are observed when smaller doses are used, only they develop more slowly. During the autopsy of animals that died from sublimate poisoning, particularly sharp changes are found in the gastrointestinal tract. The mucosa of the stomach and intestines is sharply hyperemic, inflamed, ulcerated in places, especially in the large intestine. Ulcers are of a necrotic, diphtheritic, and dysenteric nature. The kidneys are also sharply changed. The epithelium of the tubules is degenerated, necrotic, and in places, lime deposition is observed in the tubular epithelium and in their lumen. Sublimate poisoning in humans proceeds in the same way as in experimental animals. The decisive moment in sublimate poisoning is not so much the amount of substance taken, but the speed of its absorption. Of great importance is whether the sublimate was taken on an empty stomach or one full of food, in solution or powder, whether vomiting occurred immediately, and finally the nature of the measures taken to remove the sublimate (gastric lavage, protein food: milk, egg white). Poisoned individuals complain after taking sublimate internally of pains in the epigastric region. Almost immediately after taking sublimate, profuse vomiting occurs, then liquid bloody stools with tenesmus appear. Volhard distinguishes mild, moderate, and severe cases of sublimate poisoning. The expression of the severity of the case is urine output. In severe cases of sublimate poisoning, anuria occurs from the moment the poison is introduced and lasts until the end. In cases of moderate severity, polyuria is initially observed, which is replaced by oliguria and sometimes anuria. In mild cases, polyuria occurs at the beginning of the disease and lasts all the time of the disease or is replaced by normuria. Changes in the kidneys—see Nephrosis. Changes in the gastrointestinal tract arise under the influence of two causes: 1) as a result of the direct action of sublimate on the oral cavity, esophagus, and stomach during poisoning, 2) during the subsequent excretion of mercury by the epithelium of the salivary glands and large intestine. Stomatitis, a very characteristic phenomenon, in severe cases reaches gangrenescence of individual tissue areas. In the stomach, necrosis of the wall and the formation of huge ulcers are often found. Clinically, this is expressed by bloody vomiting. In the large intestine, a severe ulcerative colitis with necrosis of the intestinal wall (its mucous and submucous membranes) and ulceration is observed. Accordingly, the feces contain blood, mucus, necrotic epithelium. The heart muscle suffers greatly from the action of the poison, which is clinically manifested by muffled tones. Blood pressure in the first days gradually rises, and drops sharply before death. Changes in the morphological and chemical composition of the blood depend on the degree of kidney damage. In severe cases with anuria, retention of nitrogenous wastes is observed [residual nitrogen up to 304 mg% (Yakovleva), urea, creatinine 10.3 mg%, and indican—23.3 mg%]. The morphological composition of the blood also changes sharply. Sublimate, even with therapeutic use, causes a sharp reaction on the part of the bone marrow. Due to fluid loss, erythrocyte count and leukocytosis are often observed. However, the number of erythrocytes drops toward the end, while leukocytosis remains persistent and has the character of neutrophilia with a regenerative shift to the left. On the part of the nervous system, headaches, general weakness, decreased reflexes are noted; the picture of azotemic uremia gradually develops. Pathological anatomy. In cases ending in death, severe necrotic changes in the mouth, pharynx, stomach, and large intestine, large dirty-gray ulcers, and mucosal edema are observed. Post-mortem anatomical changes in the kidneys—see Nephrosis. Treatment of sublimate poisoning. Gastric lavage in the first hours after poisoning. Internally, milk, egg white to bind the sublimate and convert it into an insoluble state. When vomiting has occurred, intravenous glucose solutions (from 100 to 500 cm³ of a 20–30% solution), subcutaneous administration of an isotonic glucose solution, but not physiological saline. Food rich in carbohydrates is given (rice, semolina soups, raspberry or lemon drinks with sugar). The introduction of protein food should be limited so as not to increase the amount of poorly excreted protein breakdown products. In many cases, a favorable outcome was noted after the use of diathermy or roentgenotherapy on the kidney area, as well as after decapsulation. Forensic chemical detection of sublimate is carried out by means of a whole series of reactions both in the stomach contents and in the tissues, but in the latter case, it is necessary to thoroughly boil the tissue and treat it with HCl to achieve complete dissolution. When a copper wire is immersed in such a solution, a grayish-white coating appears on it, from the addition of potassium alkali—a reddish precipitate, from the addition of an excess of alkali—a yellowish one; upon the addition of a solution of potassium iodide—a purple-red color; under the influence of hydrogen sulfide—a black precipitate. To detect mercury compounds in urine, sublimation of the dry urine residue is required.

_

a. Sublimate in disinfection practice. For disinfection purposes, sublimate is used both in crystals and in the form of so-called sublimate lozenges (tablets) weighing 1-2 g. Sublimate tablets are a compressed mixture tinted with fuchsine or eosin, consisting of equal parts of sublimate and sodium chloride. (The same dyes can also be used when preparing solutions from crystalline sublimate.) In practice, 1-2% solutions of sublimate are usually used (12.5-25.0 per bucket of water). Solutions of sublimate prepared from crystals are colorless, while those from tablets are colored pink; in both cases they are transparent and have a sweetish-metallic taste. Vegetative forms of microorganisms are destroyed by sublimate solutions of usual concentration degrees within a few minutes. The assessment of the bactericidal properties of the same solutions under practical experimental conditions is rather contradictory. The degree of disinfecting properties of the product is significantly influenced by the nature of the medium being disinfected; for example, a protein medium sharply reduces the bactericidal power of sublimate due to its affinity for proteins (formation of insoluble mercury albuminates). Sublimate in solution, by virtue of a double exchange decomposition reaction, also interacts with many other products of inorganic and organic origin: salts of alkaline-earth metals, salts of fatty acids, fats, and similar substances, resulting in the production of indifferent mercury compounds. Therefore, it is not recommended to dissolve sublimate in hard water; its combinations with soaps, fats, and similar substances are completely excluded. In order to enhance the bactericidal action of sublimate solutions and impart a certain degree of chemical stability to them, it is useful to add hydrochloric acid (it is recommended to take 3.5 HCl per 1 part of sublimate), but not sodium chloride, as is commonly accepted. The addition of NaCl to sublimate solutions as a correlating substance leads to the formation of a double salt—mercuric chloride and sodium chloride [HgCl₂+2NaCl = HgNa₂(Cl)₄], which is difficult to subject to the process of hydrolytic dissociation—the formation of free mercury ions (works of Ray, Krönig, and others). According to Smorodintsev, the disinfecting action of sublimate solutions can be enhanced by combining them with phenol (C₆H₅OH), usually added in an amount of 3%. Recent data on the sporicidal significance of sublimate, contrary to old observations (Koch), lead to a negative assessment of the product from this side; for example, according to Gegenbauer, 0.05-3% solutions kill anthrax spores within 100 days. The scope of application of sublimate for disinfection purposes is quite extensive: washing infected surfaces, spraying clothing and household items, soaking contagious linen not contaminated with excretions, etc. Sublimate solutions should be excluded from practice with respect to objects contaminated with excretions and discharges of infectious patients.

G. Chistyakov. Sublimate in histological technique. As a preserving fluid for macroscopic objects, sublimate has been used since 1810 at the initiative of Keuffel, but initially, sublimate was viewed negatively. Indeed, if the tissue being fixed is overexposed in the sublimate fixative, coarse precipitates and cell shrinkage appear in it. Precipitates during the fixation of tissues with sublimate can be of two kinds: first, in the form of so-called sublimate crystals, which apparently represent the result of the reduction of sublimate to monochloride or possibly a combination of sublimate with a phosphate alkaloid, easily eliminated by subsequent treatment with iodine; second, in the form of compounds of sublimate with nucleic acid, seralbumin, and deuteroalbumin. These latter precipitates are no longer eliminable, and the fine structure of the tissues disappears. It was also argued against sublimate that nuclei are stained diffusely and protoplasm weakly (Tellyesniczky); some types of tissue (kidney, gonads) are poorly fixed in general (Vasilevsky). Finally, it was argued that part of the cellular substance is supposedly dissolved in sublimate altogether. But all these arguments against sublimate were put forward mainly when the technique of fixation in sublimate had not yet been detailed and sublimate was used mostly in the form of pure sublimate solutions. At present, sublimate in the form of a pure sublimate solution is rarely used. Usually, sublimate is used in various mixtures (with sodium chloride, alcohol, acetic acid, formalin, etc.), and these mixtures are composed mainly with the calculation of accelerating and facilitating the process of tissue fixation with sublimate in order to avoid the precipitates and shrinkage mentioned above. "Despite the listed drawbacks, sublimate fixatives are used very widely. In cases where it is desired to reveal nuclear structures with Heidenhain's hematoxylin or when staining blood cells or differentiating various forms of connective tissue, sublimate fixatives give the best results. The best fixatives are also sublimate solutions for embryos, nematodes, amoebas, and plants, but good results can be obtained only with the strictest observance of all rules and when fixing small objects (for each mixture containing sublimate, there are its own rules of fixation and subsequent processing). The most common sublimate fixatives are the following. Saturated solution of sublimate in a 0.9% aqueous solution of sodium chloride. Fix for no longer than a day, then rinse slightly in water and harden in ascending alcohols. When the object reaches 70° alcohol, it should be treated with iodine to eliminate sublimate crystals. Iodine, combining with sublimate, produces easily soluble mercuric iodide. Iodine tincture is added to the alcohol until the color of strong tea; the iodization process continues until the discoloration of the iodine solution takes place. Then the excess iodine is either washed off with alcohol or removed using sodium thiosulfate (a 2.5% aqueous solution is diluted 10 times and the removal of iodine is completed in a few minutes) or the iodine can be eliminated in a solution of ordinary hyposulfite. Upon completion of iodization, the material is embedded in either paraffin or celloidin or celloidin-paraffin. Some researchers iodize not pieces, but already cut sections, but according to Krause, this can produce artifacts. With correct fixation, nuclear structures are stained excellently with Heidenhain's hematoxylin. Most often, sublimate is used in the form of Zenker's fluid: sublimate - 5 g, potassium dichromate - 2.5 g, sodium sulfate - 1 g, glacial acetic acid - 5 cm³, distilled water - 100 cm³. Fix for no more than two days, wash for a day in running water, harden in ascending alcohols (preferably in the dark) and, having brought it to 90° alcohol, iodize. A very good fixative is Helly's fluid, which differs from the previous one in that glacial acetic acid is replaced by formalin in the same proportion. Fix for 6 hours, wash for a day in running water, harden in alcohols, iodize, and embed. If it is necessary to make a supply of Zenker's fluid or Helly's fluid, only the sublimate, potassium dichromate, and sodium sulfate are diluted, while the glacial acetic acid or formalin are added just before use; the fixative is usable only once. In general, there is a huge number of sublimate fixatives for the most diverse purposes, but the ones cited are the most common.

N. Kraevsky.