Simplify the following text for a Grade 9 native English-speaking person.
Original: In his paper Observations of two persistent degrees on a thermometer , he recounted his experiments showing that the melting point of ice is essentially unaffected by pressure .
Simplified: In his paper Observations of two persistent degrees on a thermometer , he wrote about his experiments . He could show in his experiments that the melting point of ice was basically unaffected by pressure .