Sentence:  ... taking a blue and white soda-powder, [she] mingled the same in water, and encouraged me to drink the result. It might be a specific for seasickness, but it was not for home-sickness. The fiz was a mockery, and the saline <WSD>refrigerant</WSD> struck a colder chill to my despondent heart. 
Meaning of the word marked with <WSD> tags:  That which makes cool or cold, such as a medicine for allaying the symptoms of fever.