What do the letters “Xi” on the reagent bottle label mean?

There are thousands of types of chemical reagents, which play an important role in medical, industrial, environmental governance and other fields. Most chemical reagents are dangerous and are generally classified by the English letters on the label of the reagent bottle. Do you know what the letter “Xi” on the label means?
Safety is relative. As an experimenter, we often come into contact with chemical reagents and need to understand the characteristics of various reagents. The letters “Xi” on the bottle label represent harsh chemicals. Such agents are usually mainly local damage, and can cause systemic reactions when the stimulation is too strong.
The solubility and concentration of chemical reagents determine the degree of damage to the lesion. The solubility is related to the site of action of the poison, while the concentration is related to the degree of the lesion. Ammonia and hydrochloric acid with high solubility, when they come into contact with the moist conjunctiva of the eyeball and the mucosa of the upper respiratory tract, immediately attach to the local area and cause irritation; chlorine and sulfur dioxide with moderate solubility only invade the eyes and upper respiratory tract at low concentrations, while at high concentrations, they affect the whole body. Respiratory tract; low concentrations of nitrogen dioxide and phosgene are less irritating to the upper respiratory tract, easy to enter the deep part of the respiratory tract and gradually interact with water to irritate and corrode the lungs, often causing pulmonary edema. Liquid irritant poisons can cause burns when they directly contact the skin and mucous membranes.
Experimenters must observe the letters on the label of the reagent bottle before the experiment to understand the performance of the reagent, and take precautions when handling such chemical reagents to ensure their own safety.