Sept. 1, 1899.] THE TROPICAL AGRICULTURIST, 
151 
borundum, and possess the characteristic metallic-grey 
colour of natural graphite ; but iu size and form it so 
closely resembles the original crystal as to bo, in fact 
its skeleton pseudomorph iu graphite. The graphite 
formed in the core is usually not so well defined, or 
distinct, as in that from carbsrundum, most of being 
disseminated through the body of the iadividual 
grains in which it is found, the amount contained 
in any oue ^ain varying with the precentage of 
impurity originally present. In some instances the 
entire mass of the grain is converted into beautiful, 
graphyite this occuring, I think, in cases where the 
grain is lagely composed of slate, and it sometimes 
happens that one-half of the grain is completely 
converted, while the remainder is changed but little. 
These two seemingly distinct method of producing 
graphite from carborundum and from coke, are in fact 
indentically the same ; the first step in each is the 
formation of a carbide, the second its destruction. In 
making carborundum, silica and coke are mixed in the 
correct praportions to produce a true carbide, when 
heated iu the electric furnace, without an excess of 
either constituent. In making this mixture, account 
is taken of the impurities oontaiued in the 
coke, and the silica reduced proportionately. In the 
case of the core there ia a natural mixture that pro- 
duces a carbide from a portion of the carbon. The 
carbides formed under both of these conditions decom- 
pose when heated to a certain temperature above that 
at which they were formed. 
This method of manufacturing graphite I would 
define as consisting in heating carbDn in association 
wish one or more oxides, to a temperature sufficiently 
high to cause a chemical re-action between the cons- 
tituents, and then continuing the heating until the 
combined carbon separates iu the free states. It ia 
not, however, limited to the use of oxides, as pure 
metals; their sulphides and other salts may housed, 
but for various reasons the oxides are to be preferred. 
Theory of Formation 
All of the methods of manufacture, thus tar known; 
contain the same underlying fundamental principle. 
Each of the six methods described be Muir, as well 
as my own method, contain as a part of the process 
the expulsion or liberation of the carbon from a 
chemical association with one or more elements, and 
this occurs under conditions unfavourable to, or 
absolutely prohibitive of its re-association with the 
same or other elements. It is cast out free to take 
until itself such physical or other properties as, we 
must assume, properly belong to it in the free state, 
when formed under normal conditions. It lias been 
shown by Moissan, that, when subjected to great 
pressure, at the moment of separation from cast-iron 
carbon has those distinctive characteristics that cause 
it to be called diamond; while Scheele showen in 
1778, that the same carbon, separating from the iron 
without pressure, takes the graphitic form. Amor- 
phous carbon, the third allotropic form, never occurs 
pure, and is invariably produced from carbor- 
held in chemical association with other elements, 
under conditions favourable to free chemical action 
between it and other elements. 
The production of graphite by Eose's method — 
heating a diamond bedded in charcoal to the melting 
point of case iron — is a beautiful illustration of the 
return of a body under strain to the form it takes 
under normal conditions. It will be noted that the 
diamond was heated to the teperature at which it is 
known to form, as shown by Moissan's experiments; 
also that it was fairly well protected from chemical 
action. 
The statement in the " BncyclopsediaBritanica" that 
both diamond and amorphous carbon are converted 
into graphite, when heated by a powerful electric 
current, is very commonly held — indeed I might say 
universally, — although Berthelot concluded from his 
investigations, that heat alone is without influence 
on carbon; that is to say, graphite ia not changed to 
amorphous carbon, nor the amorphous to graphite, 
when heated to witness in an atmosphere of hydrogen 
■ or chlorine. That diamond will change to graphite, 
Tvhen protected from chemical influences, under the 
influences of high temperature is undoubtedly true, 
and, indeed, is what might be expected from other 
known facts ; but that pure amorphous carbon will 
change to graphite as the simple result of heating, 
is not proven, and certainly it does not occur at, below, 
the temperature necessary for the transformation of 
the carbon in a carbide to graphite. 
From the facts in hand I have deduced the following 
theory : — 
1 Graphite is the form carbon assumes, when freed 
from chemical associations, under conditions of low 
pressure and protection from chemical influence. 
2, Diamond is the form carbon assumes, when freed 
from chemical associations, under conditions of high 
pressure and protection from chemical influence. And| 
by inferencei 
3. Amorphous carbon is the form carbon assumes, 
when freed from chemical associations, under condi- 
tions of low or high pressure and exposure to chemi- 
cal influence. 
This theory does not, however, account for all of 
the observed facts, and must be supplemented by the 
hypothesis that catalysis occurs, under certain condi- 
tions, during the transformation of amorphous 
into graphatic carbon. The amount of graphite pro- 
duced in the core of a carborundum furnace, and also 
in graphite articles I have made, is much too great 
to be accounted for by the theory that it is formed 
by the dissolution of the fixed carbides, formed by the 
contained impurities and carbon sufficient to satisfy 
the chemical formula, The most probable and satis- 
factory explanation is that a catalytic action occurs — 
a progressive formation and dissolution of carbides. 
The temperature being much above the point of 
volatilisation of silica, and all other possible impuri- 
ties, a rapid dissipation of the active agents takea 
place, and is completed, in this case, before the 
conversion of all of the amorphous carbon can occur. 
Commercial Manufacture. 
As the result of my investigations and deductions, 
I think the only commercial way to make graphite ia 
by breaking up a carbide by the action of heat. The 
carbon should be freed from chemical combination by 
what might be termed the evaporation of its associated 
elementary substances. 1 have secured patents 
covering this method, and these have been made the 
basis for the organisation of an incorporated company 
bearing the name " Acheson Graphite Company. 
The company has now under way the erection of 
works at Niagara Falls where necessary electrict 
current will be obtained from the Niagara Falla 
Power Company. 
Several distinct forms of the product will be pro- 
duced. One consists of forms or articles, made out 
of amorphous carbon, with the desired amount of 
impurity added thereto, which will afterwards be 
heated in an electric furnace, and converted, more or 
less, into graphite. I have been carrying on this line 
of manufacture for a year or more, using the furnaces 
of the Carborundum Company to produce the gra- 
phitisation, the articles having first been made by the 
arc-light carbon manufacturers. Over 200,000 carbon 
electrodes, measuring 15 inches in length, with about 
1 inch cross-sectional area, were made for use in the 
Oastner alkali process, nearly one-half of them having 
been shipped to Europe, to be used for this work in 
England and Germany. The life or efficiency of these 
graphitised electrodes is many times that of the same 
electrodes ungraphitised. I have also graphitised 
some tons of carbon plates, to be used ia making 
dynamo and motor brushes, and a large variety of odd 
forms and sizes for divers purposes. 
Another product — the one which will probably be of 
greatest importance — is an intimate mixture of pure 
amorphous carbon and graphite in fine powder. This 
will be put on the market for paint and foundry facings 
and, as it has been formed at an extremely high tem- 
perature, it is quite pure, and posseaes all of the quali- 
ties desirable for the purposes for which it is intended. 
It is not the present intention of the company to 
enter into the manufacture of their product into 
finished form for the general market, but rather to 
encourage those who are now engaged in making 
