The ‘Best Crimea Set of Blowpipe Apparatus’ mineral testing kit was made by the Truro firm of J. T. Letcher. It contained everything needed to enable mining engineers and geologists in the field to test and identify minerals on the spot. Individual minerals have specific characteristics, for example their colour, hardness, transparency and specific gravity. They also behave differently in the heat of a flame, and this is where the blowpipe comes in. The pipe consists of a brass tube with a wooden mouthpiece at one end and a very small opening at the other which blows a narrow jet of air into a flame. It increases the temperature of a Bunsen burner or candle and can be aimed like a miniature blow-lamp. Using the blowpipe involves breathing in through the nose while simultaneously blowing out through the mouth and maintaining a constant supply of air in the cheeks. An American geologists’ manual from the 1950s assured readers that ‘this is really very easy’.