original_query: What is the temperature at which the sample's density was determined?
query: What is the temperature at which the sample's density was determined for specific gravity?
answer: The temperature at which the sample's density is determined is represented by Ts in the notation (Ts/Tr), where Tr is the temperature of the reference (water).  For example, SG (20 °C/4 °C) indicates the sample density was measured at 20 °C.