20 = On the Manufacture and Uses of Animal Charcoal. 
From the foregoing observations it is evident, whether animal 
charcoal is intended for painting or clarifying, that which con- 
tains the greater proportion ef carbon is to be preferred; and 
this proportion is always easily discovered, by the application of 
muriatic acid to the coal. This acid dissolves the calcareous 
salts and the lime; after which the purged coal remains alone. 
It is then dried and weighed :—should it equal forty- hundredths 
of the analysed coal, it is very fit for painting and clarifying ; but 
the painters require it much finer than the refiners. 
Many refiners, who make advantageous use of animal black, 
have wisely judged that it might servé more than once. So that 
when it has lost its effect as a filtering clarifier, they wash it well 
in a great quantity of water, and calcine it again with or without 
the addition of animal matter. They have remarked, that this 
coal, twice or thrice calcined, was more advantageous, and clari- 
fied syrups better, than that which had been ealeined only once. 
The manufacturers of bone-black are, consequently, interested in 
buying up the coal from the refiners (after they have made use 
of it), to calcine it over again. 
We have remarked, that bone-black was the better for con- 
taining a great quantity of carbon: that is true, but that is not 
all; it is indispensable that the mixture of these different ele- 
ments be exact, and, above all, that it be well powdered. For 
this purpose, some manufacturers make use of a pounding-mill, 
like the paper-makers ; others, mill-stones; and some, cylinders. 
All these methods are good, and the nature of the situation must 
decide on which. Now, some manufacturers grind the bone- 
black dry, while others make use of water; and this latter method 
is both more expeditious and wholesomer for the workman; 
after that, it is dried before being offered for sale. 
In sugar-houses bone-black is sometimes employed as a sim- 
ple filter, and in this case they only pour the syrup on the moist- 
ened animal coal: but when required as a clarifier, it must be 
boiled up with the sugar, in the proportion of one-tenth to the 
quantity of sugar to be clarified. Before the sugar, dissolved in 
a sufficient quantity of water, has been boiled, and brought to the 
consistence of syrup, the coal is poured, little by little, into the 
boiler, After seven or eight minutes’ longer boiling on the fire, all 
is thrown together into a woollen bag disposed for that purpose. 
The syrup at first passes a little coloured by the coal it carries 
along with it; but then they pour it back into the bag, and it 
runs out clear. 
Syrups worked with coal yield a much more abundant crystal- 
lization, and of a very superior quality, to syrups worked with- 
out it. - 
It is to M. Lowitz we owe the discovery of the property of 
powdered 
