● 用途：
    制革计：测定制革溶液单宁酸的浓度之用。
    乳汁计：即牛奶表，用以测定牛奶和马奶之浓度。
    防冻液浓度计：适用石油、交通等单位对防冻液溶液测定。
    土壤计：供农林、水利、建筑等部门对土壤分析之用。

● Applications:
Tannometers:Used to determine the tannic acid aoncentration of tanning solution.
Milk hydrometers:Used to determine the concentrations of milk and hrse milk.
Hydrometers for antifreeze solution:Used to determine the antifreeze solution by the departments of petroleum and transportation,etc.
Soil hydrometers:Used to analyse the soil by the departments of farming, forest, water conservancy, architecture,etc.
Soya-bean milk hydrometers:Used to determine the concentration of soya-bean milk.