Which acid burns skin
Chemical Burns - StatPearls - NCBI Bookshelf
Continuing Education Activity
Healthcare professionals should be knowledgeable about chemical burns from exposure to acids (pH less than 7), alkalis (pH greater than 7), and irritants to recognize, manage and care for these common types of injury. Chemical burns are the result of exposure to a variety of substances commonly found in the home, workplace, and surrounding environment. The burn may be obvious, for example, from a direct spill or other exposure, or more covert, especially in children. Chemical burns can cause short-term, long-term, and lifelong health problems, especially if undertreated. Occasionally, they can result in premature death, especially if ingested in an attempt to self-harm. This activity reviews the pathophysiology and presentation of chemical burns and highlights the role of the interprofessional team in its management.
Summarize the various possible causes of chemical burns.
Describe the physical exam of a patient with a suspected chemical burn.
Review the management options available for patients presenting with chemical burns.
Explain the importance of interprofessional team strategies for improving care coordination and communication to aid in prompt diagnosis of chemical burns and improving outcomes in patients diagnosed with the condition.
Access free multiple choice questions on this topic.
Healthcare professionals should understand chemical burns from exposure to acids (pH less than 7), alkalis (pH greater than 7), and irritants to recognize, manage and care for these common types of injury.
Chemical burns are the result of exposure to a variety of substances commonly found at home, the workplace, and the surrounding environment. The burn may be obvious, for example, from a direct spill or other exposure, or more covert, especially in children. Chemical burns can cause short-term, long-term, and lifelong health problems, especially if undertreated. Occasionally, they can result in premature death, especially if ingested in an attempt to self-harm.
Common causes of chemical burns include the following:
Acids: Sulfuric, nitric, hydrofluoric, hydrochloric, acetic acid, formic, phosphoric, phenols, and chloroacetic acid
Bases: Sodium and potassium hydroxide, calcium hydroxide, sodium and calcium hypochlorite, ammonia, phosphates, silicated, sodium carbonate, lithium hydride
Oxidants: Bleaches like chlorites used in the home, peroxides, chromates, magnates
Miscellaneous: White phosphorus, metals, hair coloring agents, airbag injuries
Vesicants like mustard gas
Chemical burns occur commonly in children who explore at their "cruiser" level. Many households keep toxic chemicals under the sink or in other low-lying locations where a child may access them. Additionally, in the workplace or home environment, an individual may contact one or more chemicals that have the potential to cause external or internal injury, either because of unawareness of exposure or casual contact.
In the last few years in the United Kingdom, there have been many caustic chemical assaults on women.
Children tend to suffer chemical injuries in the home; whereas, adults suffer chemical injuries in the workplace.
Chemical burns cause damage as a result of irritant properties, acidity/alkalinity, concentration, form, amount of contact, the length of exposure, and location of contact. For example, contact with a mucosal surface such as the eye is likely to cause earlier and more extensive damage than contact with intact skin where there may be some barrier protection. After inadvertent or intentional ingestion, there will be prompt contact with the mucosal surface and both direct and absorptive toxicity.
After exposure to an alkaline agent, the -OH moiety causes injury due to liquefaction necrosis, which leads to often irreversible changes in the protein matrix. Additionally, there is vascular damage that can create a local or systemic effect.
Acidic agents cause coagulation necrosis, which leads to cytotoxicity. Additionally, there are mucosal or skin changes that may prevent further toxicity and limit absorption.
Overall, alkaline agents are more toxic than acidic agents, due to the irreversible changes in protein and tissue damage.
History and Physical
The most common findings represent structural changes to the tissue directly affected, for example, the eye, oral mucosa, skin, esophagus, and lower intestinal system, especially the stomach and pylorus, respiratory system, among others. In children, ingestion is generally the most worrisome event, because of changes, both short-term and long-term, often leading to extensive tissue death. Eye exposure, either acid or alkali, represents a significant acute injury. Copious irrigation is necessary, and measuring pH is appropriate, although rarely informative.
Direct examination of external exposure sites is mandatory, and if there is ingestion, endoscopic evaluation is necessary. In the instance of hydrofluoric (HF) acid exposure (see treatment below), monitoring of serum calcium and magnesium levels is critical to prevent chelation with the fluoride ion and cytotoxicity. With most other topical exposures, observation and serial monitoring of changes are sufficient.
Any gastrointestinal (GI) exposure must be seen by an experienced endoscopist who may need to perform serial evaluations to document healing. Likewise, eye injuries must be examined by an experienced ophthalmologist who will follow up with the patient sequentially and guide additional therapy.
With ingestions, especially when concerned about systemic absorption, laboratory evaluation (complete blood count [CBC], platelets, electrolytes, calcium, magnesium, arterial/venous blood gas, liver and kidney studies, lactic acid level, and, occasionally, coagulation studies) may be indicated. Radiographic studies, especially including an upright chest film, may help to determine if there is the presence of free air, which is suggestive of a perforation. Non-contrast CT may be used if there is concern about mediastinal free air, resulting from a perforation after exposure. Previously, a radio-opaque contrast was used, but this should be avoided in suspected perforation.
Treatment / Management
Copious irrigation of affected external areas is mandated. Endoscopic examination best explores internal injuries after ingestion. If there is concern about ingestion of disc or other flat batteries, radiographic assessment is mandated. It would be unusual that CT scanning would be needed, and MRI studies are interdicted. Ultrasonography in experienced hands may provide answers as to location as well.
It is not appropriate to introduce emetic agents or "neutralizing" agents into the treatment regimen after ingestion. There is high concern about aspiration, increased tissue damage with retching, and a strong possibility of exacerbating a bad situation. There is no current recommendation of systemic medications such as steroids, antibiotics, or prophylactic renal/hepatic therapies.
HF acid, among all the exposures mentioned above, can be treated with copious irrigation and application of a paste (commercially available and often supplied in an industrial setting where HF may be used commonly or made in the emergency department with powdered calcium gluconate and surgical lubricants). Some have recommended benzalkonium chloride solution. When applied, the treating clinician should use barrier protection. In some circumstances, intradermal or intraarterial injections of calcium (gluconate strongly preferred) have been used. Relief of pain is a good marker of the efficacy of treatment. Monitoring of calcium and magnesium levels is important. Oral ingestion, often in the context of suicidal behavior, is likely to be fatal and may be treated with lavage. Monitoring of heart rhythms and electrolytes, including calcium and magnesium, is necessary. Lavage may be helpful, especially if calcium salts are used.
Disc batteries have the potential to leak alkali and cause local, generally esophageal, burns. This is typically seen in children and will require endoscopic management and radiographic tracking of location. Early removal is strongly recommended. If the battery has passed the pylorus, watchful waiting, and inspection of stool for passage are appropriate.
The prognosis depends on the type of chemical and extent of the injury. Most small lesions heal well, but larger wounds often do not heal and can develop into scars. Hydrofluoric acid burns have typically been associated with loss of digits.
Chemical injuries to the eye are the most serious, resulting in severe scarring and permanent loss of vision.
The most common complications are pain and scarring. Vision loss occurs when the eye is injured. Most patients require multiple doctor visits, and many patients require skin grafts to alleviate the scars.
Postoperative and Rehabilitation Care
Except for first-degree burns, all other burns require some type of follow-up. Skin burns need to be evaluated every 2-4 days until there are signs of healing. Patients with eye burns need to be seen in 24 hours.
For those who suffer a burn to the esophagus, endoscopy has to be repeated in 14-21 days to ensure that there is no stricture formation.
Besides a general surgeon or a burn specialist, other consultants involved in the care of these patients include an ophthalmologist, ENT surgeon, gastroenterologist and a pediatrician.
Deterrence and Patient Education
To avoid chemical injury in children, parents should keep all dangerous chemicals out of reach of the children.
Individuals who have attempted suicide with chemicals need a psychiatric referral.
Pearls and Other Issues
Chemical burns have the potential to impair short and long-term health and, especially when the eye or esophagus are involved, severely alter the individual's well-being. The clinician must be vigilant to monitor even minor appearing burns, especially with HF acid, as what initially appears to be minor may have serious side effects.
Enhancing Healthcare Team Outcomes
Because burns can occur on almost any part of the body, specific guidelines in the management of each organ system are lacking. However, there is expert evidence on managing the patient as a whole. However, there still remain several gaps in the early management of chemical burns. What solution to rinse the skin or the eye and when to debride are two issues that continue to be debated. But there is no debate that the eye should be rinsed thoroughly, and the patient must be seen by the ophthalmologist. Because burns can affect all organ systems an interprofessional approach with interaction is necessary to avoid the high morbidity of the disorder.
Since most burn patients are managed in a burn unit, the role of the nurse is vital. Often these professionals are the first to identify burn-related complications like infections, melena, difficulty swallowing, eschar formation, and declining urine output. The pharmacist should be closely involved when burns are caused by medications like podophyllotoxin, formic acid, or topical salicylic acid. Knowledge in managing topical burns, especially in children can help prevent disability. (level 3)
The outcomes following a chemical burn depend on the chemical, extent of the burn, comorbidity of the patient, and time to intervention. Some chemicals are more harmful than others, but chemical burns to the eye are always serious. Because chemical burns can cause poor cosmesis and functional disability, a team approach to management is vital. (Level 5)
Severe alkali burn to the right eye. Being lipophilic, alkali solutions penetrate the eye more rapidly and have the potential to penetrate ocular tissues. Acids, on the other hand, cause precipitation of proteins which creates a barrier and prevents further (more. ..)
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Side Effects, Precautions, and Safety
Hydrochloric acid is a strong acid that can cause severe chemical burns if it comes in contact with your skin.
Toilet cleaners, pool chemicals, and some fertilizers are common household sources of hydrochloric acid. Your stomach acid is also primarily made up of hydrochloric acid, but a protective mucus protects the inside of your stomach from damage.
Hydrochloric acid burns are one of the most frequently treated types of chemical burns. Even though only a small fraction of total burns are chemical burns, chemical burns are responsible for one-third of burn-related deaths.
Keep reading to find out the most common symptoms of a hydrochloric acid reaction and the steps you should take immediately if you spill hydrochloric acid on your skin.
Hydrochloric acid can cause damage if it comes into contact with your lungs, eyes, stomach, or skin.
If hydrochloric acid comes into contact with your skin, it can cause:
- chemical burns
If hydrochloric acid comes into contact with your eyes, it can cause:
- vision loss
- potentially permanent eye damage
- eye discharge
Chemical burns on your skin can be mild or severe depending on how much the acid is diluted and how long the acid is in contact with your skin.
Like with other types of burns, chemical burns can be categorized based on how deeply they penetrate your skin.
- First degree. These burns only damage your top layer of skin. They often cause red and tender skin but rarely cause blisters.
- Second degree. Seconddegree burns extend into the deep layers of your skin. They often cause painful red blisters and may need medical attention.
- Third degree. These burns extend through your skin and into the fat tissue below. They may not cause pain if nerves become damaged but require immediate medical attention.
- Fourth degree. Fourth degree burns extend into deep tissue layers like your tendons or bones. They may cause damage that requires limb amputation.
It’s critical to take proper precautions when handling potentially dangerous chemicals. Hydrochloric acid has the potential to cause life threatening burns.
A 2014 case study describes an accident where a 50-year-old pool cleaner’s skin was exposed to chemicals containing hydrochloric acid. The incident caused fourth degree burns that eventually led to amputation.
Symptoms of inhaling and ingesting HCl
Inhaling hydrochloric acid has the potential to seriously damage your lungs and respiratory system. It may lead to:
- nose irritation
- upper respiratory tract damage
- breakdown of lung tissue
- shortness of breath
- chest tightness
- rapid breathing
- fluid buildup in your lungs
Ingestion of hydrochloric acid may lead to:
- potentially permanent lip and mouth damage
- esophagus or stomach damage
- difficulty swallowing
Hydrochloric acid burns can cause major injuries. Follow the steps below right away and call 911.
If your skin comes into contact with hydrochloric acid, it can result in severe burns that need medical attention.
If you have a chemical burn, you should follow these steps immediately:
- Flush your skin of the hydrochloric acid by running cool water over the affected area for 10 minutes.
- Remove any clothing or jewelry that came in contain with the acid.
- Cover your burn with a sterile gauze bandage.
- Flush the area again if needed.
- Contact 911 or seek immediate medical care if your burn is severe.
Burns larger than 3 inches across or those on your hands, feet, face, or groin require prompt medical attention.
Hydrochloric acid makes up the majority of the acid in your stomach. Cells in your stomach called parietal cells produce this acid and secrete it into your stomach to help break down food.
Even though hydrochloric acid can cause severe burns to your skin, your stomach is protected by a protective mucus layer produced by the cells that line your stomach.
When your body’s protective barrier of mucus is disrupted, stomach ulcers may form. Long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) and bacterial infections are the most common causes of stomach ulcers.
Skin care products don’t contain hydrochloric acid. However, many skin care products contain another acid called hyaluronic acid.
Many people mistake hyaluronic acid for hydrochloric acid. Even though the two acids sound similar, they aren’t related.
Here’s an overview of how these two acids are different:
- a strong acid that can cause chemical burns
- naturally found in your stomach
- used in pool cleaners and tile cleaners
- helps your body break down food
- naturally found in your skin, eyes, and joints
- often found in skin care products
- found in some eye drops
- used in the treatment of cataracts
Hydrochloric acid can cause a severe chemical burn if it comes into contact with your skin. It’s found in pool chemicals, some fertilizer, and some household cleaners.
You can reduce your chances of having a chemical burn by taking the proper precautions when handling dangerous chemicals:
- Keep chemicals in a high place not reachable by children.
- Wear protective glasses and clothing when handling chemicals.
- Keep all your chemicals in sealed containers.
- Minimize your use of dangerous chemicals.
- Leave all chemicals in labeled containers.
Sulfuric acid - Chemwatch
What is sulfuric acid?
Sulfuric acid is widely used in industry and is used in the processing and production of many hundreds of different compounds. It is a very caustic and strong mineral acid with the molecular formula h3SO4, also known as "oil of vitriol". It is a colorless to slightly yellowish viscous liquid, soluble in water at all concentrations. You may sometimes find it to be dark brown, as it is often dyed during the industrial production process to warn people of its dangerous nature. Sulfuric acid is a diprotonic acid and can exhibit different properties depending on its concentration. As a strong acid, sulfuric acid corrodes metals, stones, skin, eyes, flesh, or other materials. It can char the wood (but will not cause a fire). These effects are mainly due to its strong acidity and, in the case of concentration, strong dehydrating and oxidizing properties.
Sulfuric acid can be found in many situations - it's a component of acid rain and battery acid, and it can even form when some cleaners are mixed with water.
What is sulfuric acid used for?
The short answer is a lot!
Sulfuric acid is most often used in the production of phosphate fertilizers. It also finds use in the manufacture of explosives, other acids, dyes, glues, wood preservatives, and car batteries. It is also used in oil refining, metal pickling, copper smelting, electroplating, metal processing, and the production of rayon and film.
Sulfuric acid hazards
Sulfuric acid has been classified by the International Agency for Research on Cancer as a human carcinogen. Your lungs and teeth can also be damaged by long-term exposure to aerosolized sulfuric acid.
In addition, sulfuric acid has a wide range of effects on the body and is especially corrosive to eyes, skin, respiratory tract and tooth enamel, so handle with care! This is known to result in:
- irritation of the eyes, leather, nose, throat
- pulmonary edema,
- Earos and skin burns,
Inhalation of sulfuric acid can cause burning, sore throat, cough, shortness of breath, shortness of breath and pulmonary edema, and it is important to note that these symptoms may appear later.
Skin contact with sulfuric acid may cause redness, pain, blisters and severe skin burns.
Contact with eyes may cause redness, pain and severe deep burns. Swallowing is even less recommended and may result in abdominal pain, burning sensation, shock, or collapse.
Sulfuric Acid Safety
A number of safety precautions should be taken after exposure to sulfuric acid as it can cause serious adverse health effects.
If the patient has swallowed sulfuric acid, DO NOT induce vomiting. If they vomit on their own, make sure you tilt them forward or lay them on their left side, preferably with their heads down so they don't choke on their vomit. Do not give them milk, butter, or anything containing alcohol. Emergency eyewash and eyewash shower in the laboratory.
Got you in the eye? Open your eyelids immediately and flush your eyes continuously with running water. Make sure your eye is completely flushed, keep the eyelids apart and away from the eye and move the eyelids, lifting the upper and lower eyelids from time to time.
If it comes into contact with your skin, immediately take off all contaminated clothing, including shoes. Then rinse your skin and hair with running water (with soap, if available).
In case of inhalation of sulfuric acid fumes or products of combustion, remove the patient from the contaminated area and lay him down. Keep them warm and rest.
Chemwatch has the largest collection of Safety Data Sheets (SDS) in the world. For a free copy of Chemwatch's SDS for sulfuric acid, click the button below.
Download Chemwatch Mini SDS
【Burning and caustic substances. Hydrohalic acids and other substances 】
(27) Hydrohalic acids. Hydrochloric acid (an aqueous solution of hydrogen chloride), in comparison with other acids, does not act in a particularly strongly corrosive way on the outer covers, even when in concentrated form; causes an itchy, painful redness on the skin, but usually the action does not penetrate deeply. The skin becomes hard, dry and shallow, the sharpness of touch is lost; after a while, the top layer peels off. Concentrated hydrochloric acid is corrosive to the eyes and mucous membranes.
Hydrobromic and hydroiodic acids act like hydrochloric acid.
Gaseous hydrochloric acid (hydrogen chloride: irritates mucous membranes, causes runny nose, catarrh of the pharynx, larynx, bronchi, sometimes coughing up blood, inflammation of the eyes, clouding of the cornea, set teeth: in addition, destruction of the nasal concha and perforation of the nasal septum have been observed
Conditions of poisoning: gaseous hydrochloric acid is released when glazing earthenware with table salt, when soldering (from a soldering solution), when pickling metals with concentrated hydrochloric acid, vulcanizing rubber with sulfur chloride, when obtaining artificial fertilizers, carbonizing fabrics, in smelters during chlorinating firing Sprayed hydrochloric acid hits workers when embossing the etched pattern. 0005
First aid. To neutralize the inhalation of hydrochloric acid vapors, you can breathe a solution of bicarbonate of co2, sprayed into a thin mist with a spray gun.
Hydrofluoric (hydrofluoric) acid is extremely strong. Stah2) writes on this occasion: “It has a more harmful effect on the respiratory organs and skin than all other acids. The effect of an aqueous solution of this acid does not become noticeable immediately; after 1/2-1 days, even on the skin covered with calluses, an extremely painful inflammation is observed, often leading to suppuration and healing very slowly. Anhydrous hydrofluoric acid is especially strong. white spreading spot, there are pains that deprive even sleep.At the same time, a deep-penetrating, pus-filled, bubble with rather "thick walls" is formed. The pains stop only after a day, sometimes they last up to three days. Inhalation of hydrofluoric acid vapors causes serious illnesses, which, for example, happened to the Knox Louyet brothers, who worked with hydrofluoric acid for scientific purposes, died from inhalation of its vapors.
Hydrofluoric acid is used for the preparation of antimony fluoride, for engraving on glass, for bleaching and leaching furniture reeds; also obtained from the processing of crude phosphate Precautionary measures. Vapor suction, respirators, skin greasing, rubber fingers or rubber gloves.
First aid for injuries. Immediate immersion of the affected area in a solution of ammonia or 10% solution of ammonium carbonate. With the onset of pain, 1-2 hour baths from the solutions have subsided or the application of compresses from them.
 When evaporating a weakly acidic concentrated solution of silver fluoride, water vapor of hydrofluoric acid fell on Professor R.'s fingertips, with which he held a platinum spatula with a somewhat short handle. During the work, which lasted less than half an hour, pains appeared under the nails, which quickly intensified. Two days later, suppuration appeared, and two nails had to shine.
 While pouring anhydrous hydrofluoric acid into a fluorine apparatus, a cowardly employee spilled some of the acid on Professor R's arm. In a few seconds, the skin on the affected areas peeled off, exposing the meat, resulting in a third-degree burn, the healing of which with the formation of scars continued for within four weeks: after 24 hours blisters formed around the most burned place, as with a second-degree burn, which had to be opened and removed, resulting in a rather extensive wound surface.
 A married couple wished to use hydrofluoric acid to remove the inscription from the porcelain closures of beer bottles. With the first three fingers of his right hand, the husband took a rag, moistened it with acid and began to rub the shutter, and the inscription easily disappeared. After a while, he felt a slight burning sensation, and therefore left the work; the wife, putting on an old leather glove, continued cleaning in the same way and in turn soon felt a burning sensation. A few hours later, at night, the pains of both became so severe that a doctor was called. He found the ends of three fingers very inflamed: black, large blisters with ichorous contents had formed. The pain was terrible, barely bearable. Healing was very slow, with severe suppuration. nails are gone.
(28) Carbolic acid (phenol) often causes weeping lichen on the skin in physicians, nursing staff, and dressing factories.
 V one railroad worker burst a cylinder of carbolic acid and the acid fell on the index finger of his left hand. turned black and dead, and, since his immobility interfered with his work, the doctor had to remove his finger.0005
 Chemical examination of two automobile helmets that caused a forehead rash revealed that the lining consisted of a strip of linen covered with an oilcloth-like brown mass containing phenol derivatives. From the action of heat and acidic sweat, free phenol was released and acted on the scalp.
(29) Hydrofluorosilicic acid acts similarly to hydrofluoric acid, but weaker (see ).
(30) Concentrated formic acid is corrosive to the skin.
(31) Picric acid. Acting in the form of dust, it irritates the mucous membranes of the nose and eyes; causes itching on the skin and spotted, scarlet fever-like rashes.
Pyrosulfuric acid, see sulfuric acid.
(32) Sulfuric acid poses a number of dangers. In concentrated form, it is highly corrosive. Getting on the skin, it first causes a feeling of warmth, which quickly turns into a feeling of intense burning. Acid is able to quickly penetrate into the depths of tissues. If you wash it off very quickly, after
1-3 seconds, the effect is not so strong, affecting only the top layer of the skin itself. With a somewhat longer action, first white, then brown streaks, resembling tanned skin, are obtained, under which deep tissue destruction occurs. After some time, the scab falls off, leaving behind a deep ulcer with sharply defined edges and a light red bottom; when suppurated, the wound heals slowly with the formation of granulations, leaving behind a large, flat scar, which remains red and shiny for a long time. Subsequently, the wound turns pale and shrinks, which, with a large amount of damaged areas, can lead to remaining severe injuries. If it gets into the eyes, sulfuric acid causes destruction so strong that the likelihood of healing without serious consequences is very small. Terrible burns are obtained in the mouth, esophagus and stomach from the pounding of swallowing sulfuric acid. Such burns almost always lead to death or from direct destruction of organs or starvation, since the scars formed in the esophagus interfere with the passage of food.
A common cause of burns is the strong acid test in a qualitative analysis, during which the test substance is heated in a vial of concentrated sulfuric acid.
Due to the rapid release of gases, like a small explosion
or due to the so-called push when cutting, the acid is often ejected from the test tube and, being in a combustible form, causes especially strong destruction. Students should be taught from the outset to hold the test tube in such a way that if acid is thrown out, no harm can be done to anyone.
Then there is a danger when diluting the acid; so much heat is given off that, thanks to the violent release of vapors, the acid can be sprayed with force around. If, as is prescribed, acid is poured into water in a thin stream, violent phenomena never occur, except when the water was hot. On the contrary, it is absolutely wrong to pour water into acid, since in this case splashing is inevitable, even if the water was cold.
 Caretaker Sch. in H.I.Z. rinsed the dishes; pouring a rather large amount of concentrated sulfuric acid into the boiling flask, he, not foreseeing anything bad, began to pour water from the water supply into it. At the same moment, part of the contents, in the form of an explosion, threw out Sch. right in the face. He managed to close his eyes in time and, since he was near the table for washing dishes, he managed to wash his entire head well, so that the damage was not particularly severe. For quite a long time his entire forehead and techs looked like they were covered with tanned skin, and the skin was very peeling. On one side of the forehead, it came to suppuration.
Every beginner should immediately understand well that some substances, when interacting with concentrated sulfuric acid, can give explosions, in which, usually, burning with acid is the main danger. These are mainly salts of chloric and immanganic acids, oxides and hydroxides of alkali and alkaline earth metals in solid form or in the form of concentrated solutions, as well as a strong solution of ammonia.
An explosion can also occur when sulfuric acid is added to substances of unknown composition.
 Dr. Vinassa. a cantonal chemist in Lugano, described the burn of his face, which he received c) during the test of pouch dirt for the presence of arsenic, in which he, according to the Naser-Ambah method, licked concentrated sulfuric acid to the substance. The entire mass was thrown out of the vessel. The wound healed very quickly after washing with a solution of bicarbonate of soda and lubricating with a solution of thiol, with the addition of C cocaine.
Student A G. n Z narrowly escaped a great danger. He heated benzene with very concentrated sulfuric acid in a rather large flask on a water bath to prepare benzene sulfonic acid. He shook the flask from time to time, and inadvertently knocked the flask on the button of his coat.