Set Contents: Lithomus Test Paper, Red, Blue, 50 sheets per case. About Change: Red: Changes to Blue with Ph8.0, Blue: turns red with Ph5.0, Test Paper Size: Width 0.3 x Length 2.4 inches (8 x 60 mm). *What is Lithomas Solution? It is used as a representative agent because it extracts the purple pigment of lithomas scorching on rocks on the Mediterranean coast and West Africa, and turns red with acids and blue. It is water-soluble