68 
POPULAR SCIENCE REVIEW. 
Annexe. Viewed as an attempt to endow tlie humble gelatin 
with some of the elegance and refinement of its more costly 
competitor, these endeavours deserve all the success which has 
attended them ; but, in the hands of some retail sellers, this 
legitimate imitation is often palmed off upon the public as 
genuine isinglass, when it assumes the character of an unjustifi- 
able imposition. 
When bones are heated without access of air, the organic matter 
of the cartilage is decomposed — oily products passing over and a 
black carbonaceous residue being left. This is known by the name 
of bone-black or animal-charcoal, and consists of carbon in an 
extremely fine state of division diffused through the inorganic 
constituents of the bones. Bone-black has a great affinity for 
several organic colouring matters, and is extensively used for 
decolourizing syrups, sugar, and other things. If a solution of 
dark brown sugar be filtered through a layer of bone-black it 
passes through perfectly bright and colourless ; port-wine may 
in a similar manner be obtained as colourless as water, without 
its flavour being- much impaired. The oil which distils over 
during the operation of calcining is known in commerce as 
“ IdippeFs animal oil ; ” it contains aniline and several other 
basic bodies, and can be employed for the production of 
colouring matters in the same way as coal-tar. 
The subject of artificial manure is one which has received 
great attention of late years. Chemists have discovered that 
the earthy constituents of bones form one of the most valuable 
foods of plants, and to supply the soil of England with the 
earthy phosphates which are annually removed from it by 
cereals and other crops, manufacturers now not only make 
use of recent bones, but avail themselves of the rich store of 
phosphatic wealth existing in the fossilized remains of extinct 
animals. The so-called superphosphate of lime consists of 
calcined bones, or coprolites,* which have been reduced to fine 
powder and then treated with sulphuric acid; part of the lime 
is removed by this process and the remaining- superphosphate 
is obtained in a form which is readily assimilated by plants. 
The manufacture of phosphorus- — -“that dark, unctuous, 
daubing mass,'” — which has now become so important and 
universal an agent of civilization, is the last product from 
bones which claims our attention. It is prepared from the 
phosphoric acid contained in bones by heating- it to a very high 
temperature with charcoal. The five equivalents of oxygen 
contained in the phosphoric acid are removed by the charcoal, 
and the phosphorus distils over. The crude product is after- 
wards purified by distillation and squeezing through chamois 
"" Coprolites are supposed to be the petrified dung of reptiles, 
