Hydroxylamine sulfate, also known as azurine sulfate, is a white crystalline powder. It is highly reducing, easily absorbs moisture in the air, and is irritating to the skin and eyes. Hydroxylamine sulfate has a melting point of 170 °C, is soluble in water, and slightly soluble in ethanol and methanol. 

It is mainly used as an analytical reagent, a reducing agent, and can also be used in organic synthesis. In addition, hydroxylamine sulfate is also used in the preparation of caprolactam, as well as as as an intermediate in medicine and pesticides, and its derivatives can be used in the production of insecticides, fungicides and herbicides.

1. Analytical reagents: Hydroxylamine sulfate is used as a reducing agent in chemical analysis, especially in the determination of trace metals.

2. Organic synthesis: It participates in organic synthesis reactions and acts as a reducing agent or oxidant for the synthesis of a variety of organic compounds.

3. Pharmaceutical intermediates: Hydroxylamine sulfate is used as a raw material for the synthesis of pharmaceutical intermediates in the pharmaceutical industry, especially in the production of certain antibiotics and anti-cancer drugs.

4. Pesticide manufacturing: It is an intermediate of certain insecticides, fungicides, and herbicides used to control pests and weeds in agricultural production.

5. Preparation of caprolactam: hydroxylamine sulfate is used in the production of caprolactam, which is an important chemical raw material used in the manufacture of polymers such as nylon 6.

6. Electroplating industry: In the electroplating process, hydroxylamine sulfate can be used as a reducing agent to clean the metal surface and improve the quality of the plating layer.

7. Other industrial applications: It is also used in the production of plastics, rubber, dyes, and other chemicals.