The blower then heats the end of the cylinder again and rapidly spins the pipe about its axis; the centrifugal effect is sufficient to spread the soft glass at the end to a radius equal to that of the rest of the cylinder.
The blower places the glass in the mould, closes the mould by pressing a lever with his foot, and either blows down the blowing iron or attaches it to a tube connected with a supply of compressed air.
When the air has forced the glass to take the form of the mould, the mould is opened and the blower gives the blowing iron with the bottle attached to it to the " wetter off."
The results given below, which are selected from a much larger series published in the Journal of the Chemical Society, were obtained by heating samples of the different coals in vacuo for several hours at the temperature of boiling water: - In one instance about i% of hydride of ethyl was found in the gas from a blower in a pit in the Rhondda district, which was collected in a tube and brought to the surface to be used in lighting the engine-room and pit-bank.
It is by the appearance of the flame that the operator or " blower " knows when to end the process, judging by its brilliancy, colour, sound, sparks, smoke and other indications.