When heated in a closed retort, bones are not converted into bone-ash, but into a body called bone-char.
Formerly the test was lined with bone-ash; at present the hearth Cupelling.
When the bone-ash has been sufficiently compressed, the die is withdrawn, and the cupel removed from the ring.
The floor of the muffle is protected with a layer of bone-ash, which absorbs any oxide of lead that may be accidentally spilt.
Coprolites are seldom used alone for the manufacture of superphosphates, but are generally mixed with bone-ash and bone dust.
The buttons are removed from the cupel with a pair of pliers and then brushed to remove adherent litharge and bone-ash.
The bone-ash is used moistened with a quantity of water, sufficient to make the particles adhere firmly together.
bone-ash varies considerably in price, but of late samples containing 70 per cent of phosphates have sold as low as £4: 10s.
bone-ash is best used in the dissolved form, as it possesses no characteristic action such as is possessed by bones.