COLLOIDAL FUEL Mr. Lindon W. Bates, in a paper read before the New York section of the American Society of Mechanical Engineers, has the following to say regarding Colloidal Fuel : Colloidal Fuel is a combination of liquid hydro-carbons with pulverized carbonaceous substances, the components so combined and so treated as to form a stable fuel capable of being atomized and burned in a furnace. It is made in three forms, a liquid, a gel and a mobile paste. The new composite is intended primarily to be used as fuel. While the designation "Colloidal" is given it because so much of the combination is in the colloidal state, the name is not scientifically adequate, since much of the solid com ponent is not reduced to colloidal dimensions. The title is, how ever, descriptive because of the important colloid-like characteris tics of the composite. It is liquid up to the ratios of oil sixty percent and coal forty percent or thereabouts. It- is a mobile paste up to the ratio of oil twenty-five percent and coal seventy five percent. All kinds of oils and solid carbons may be used The cheap coal breakages and wastes are all available. The liquid is used in the self-same , way as oil fuel and with the same apparatus, The coal particles are maintained in a state of suspen sion in the oil during the time required for the use of the fuel —days, weeks or months. (See fig. 16.)a It is of interest to read the results of a special study made Jan. 3, 1920, by Dow and Smith, Chemical Engineers, of New York City, to confirm certain technical aspects of Colloidal Fuel Grade 15, a typical grade, containing 38% mixed coal and coke,'in Mexican ,Reduced Oil, made in August, 1919, and shipped to the Imperial JapaneSe Navy in Japan : "We have examined your sample of colloidal fuel to deter mine whether electrolites cause precipitation of any of the suspended particles.
"We first tested your fuel in a glass cylinder to determine whether or not there was any subsidation, with the following results : "100 cc. of the colloidal fuel with a depth of 6" was allowed to stand for 24 hours at a temperature of 115° F. At the end of the 24 hours the very top of the fuel was analyzed and that taken from the very bottom of the cylinder.
"The top contained 33.8% in benzole.
"The bottom contained 36.4% insoluble in benzole, showing an increase of 2.6 of coal particles in the bottom over the top. This subsidation represents the particles of coal that have become destabilized since the sample was manufactured. It must not be inferred that a continuous and progressive subsidation would take place, that is, the subsidation in the second 24 hours would be only a fraction of a per cent, and would merely represent the particles which in that time had becothe destabilized. Some idea as to
the quantity can be, obtained from the fact that this sample, being five months old, shows only 2.6% of the particles had be come destabilized in that time.
.!`Three lots of the fuel 100 cc. each were then shaken up with electrolites, sodium chloride, alum and copper sulphate, 5 grams of the powidered electrolite being used to this quantity of fuel. After the three cylinders had stood 24 hours there was no per ceptible difference in the top and bottom, ,and therefore, no apparent precipitation by the electrolites.
"We have examined your colloidal fuel thinned with benzole under the ultra-microscope and find that it is filled with particle which have the Brownian Movement. We should judge that about half of the particles visible showed this action and they varied in size from those which were quiescent to others which had had an active range of 0.00325 mm. • We also passed the benzole solution of your fuel through the finest hardened filter paper and found that the filtrate con colloidal particles.
"We examined your colloidal fuel under the microscope and measured the size of the visible particles with 1000 diameter mag nification. We noted several particles field .001 of an inch across and .002 of an inch in length. There were numerous par ticles ranging from this don to invisibility. The majority of the particles appeared to be about .0001 of an inch in diameter. There is, of course, no doubt but that the particles diminish in size to that of molecules, as was shown by an examination under the ultra-microscope, and also from the fact that we know that portions of coal are soluble in mineral oils." • Colloidal Fuel enjoys several special qualities. The calorific value per unit volume is greater than that of straight oil unless coals of very low heat value and specific gravity are incorporated. The reason is that coal is heavier than oil though of less Calorific content per pound, so that the coal content most frequently raises the calorific value per unit volume. The addition of coal is not an adulteration of the oil, but it makes an increase of the heat units in the resultant gallon of liquid fuel. Thus in a composite made up of 35% by weight of pulverized anthracite coal of 14,000 B.t.u. per pound and 1.6 specific gravity and 65% oil of 18,200 B.t.u. per pound and .96 gravity, gallon of the composite has 165,000 B.t.u., while oil has 146,000 B.t.u. per gallon.