Centrifuge

“ The details of the method of determining specific gravity by the use of this apparatus are as follows:
[37]
Fill the flask shown in Figure 1 with the sample of pulp and place in the centrifuge (the Babcock milk tester mentioned above) . Place a suitable counterpoise [16] in the other receptacle of the centrifuge. Whirl for from one-half to one minute at a speed of about 1,000 revolutions per minute, that is with the handle turning about 100 revolutions per minute. Because of the air bubbles removed by whirling, the surface of the pulp will now be considerably below the top of the flask. ”

“ SAMPLE PREPARATION: 5. Remove caps from sampling tubes. Transfer the front and back sections of sulfuric acid-treated silica gel to separate 15-mL graduated centrifuge tubes. NOTE: Firm tapping of the tube may be necessary to effect complete transfer of the sulfuric acid-treated silica gel. 6. Add 10 mL of deionized water to each centrifuge tube. Cap and shake vigorously. Allow to stand 45 minutes with occasional shaking. ”

“ Place 1 spatula full of dust (approximately 0.1 cm3; the size of a small pea) to be tested in a 15-mL clear plastic centrifuge tube. Add extraction solution up to the 2-mL mark. Cap the tube and shake vigorously. 2. Allow the tube to stand for 10 minutes, or longer, with occasional shaking. NOTE: Gently heating the tube in hot water will increase the sensitivity of the test. 3. Uncap the centrifuge tube and add deionized water to the 7-mL mark. Mix and allow the residue to settle. 4. Decant or pipet approximately 3 mL of the supernatant liquid into a second tube. ”

“ The surface of this centrifuge is parabolic, so that the resultant of the centrifugal g and the Earth's gravity is always normal to the surface. When the animal moves away from the center, increasing the radius of rotation, it is exposed to increasing gravity. Motion toward the center reduces the gravity level. By this means, an animal is free to select its own gravity environment.
When the animal moves toward or away from the center, he is moving from one tangential velocity to another. He is therefore acted upon by a third force—due to Coriolis acceleration. ”

“ If larger quantities of blood are required, the animal, after puncturing the vein, should be inverted, an assistant holding it up by the legs. Blood to the volume of several cubic centimetres will now drop from the punctured vein, and should be caught in a tapering centrifuge tube, the tube transferred to the incubator at 37° C. for two hours, then placed in the centrifugal machine, counterpoised and centrifugalised thoroughly. ”

“ A glass rod, or a piece of tubing extending to the bottom of the centrifuge tube is used to defibrinate the blood. After centrifugalizing there should be at least one inch of serum above the cell sediment. The parasites develop in the upper cell layer, about 1/50 to 1/20 inch from the top. All of the parasites contained in the deeper-lying red cells die. To observe the development, red cells from this upper 1/20 inch portion are drawn up with a capillary bulb pipette. ”

“ Quantities of formulated concentrated liquid growth media or cell culture media that exceed the established consumption rates.
Microbial grade yeast extract.
Cell culture grade fetal bovine serum.
(5) 4.1: Centrifugal separators (or decantors) designed for use with biological material capable of continuous operation at a flow rate of 20 litres per hour or greater and specially designed rotors therefor.
(6) 4.2: Batch centrifuges with a rotor capacity of 10 litres or greater, designed for use with biological agents. ”

“ Centrifuge 2 min. Discard the bottom (aqueous) layer. c. Repeat the washing with two additional 2-mL portions of pH 6 buffer. Place a small glass wool plug in a chromatographic column and add 1.6 g Florisil. ”

“ Personal sampling pump, 0.1 to 0.5 L/min, with flexible tubing. 3. Ion Chromatograph with conductivity detector, cation column and guard, and cation micromembrane suppressor (see p 6016-1) . 4. Syringes, 10-mL, polyethylene, Luer tip. 5. Centrifuge tubes, 15-mL, graduated, plastic with screw caps. 6. ”

“ When a liquid, containing solid matter, is fed into the drum, which is already running at high speed, the liquid is thrown, by the centrifugal force, against the peripheral surface of the drum and escapes through the perforations, leaving the solid matter behind. Where large crystals are in question, as for instance in sugar factories, the centrifugal machine can be employed without any additional precautions, the liquid being expelled and the crystals being practically dried by keeping the machine running a short time longer. ”

“ Centrifugal force must always be balanced by centripetal force. The difficulty is to understand what force counterbalances the centrifugal force of the rotating material of the vortex-atom. It is not because the centrifugal tendency of the rotating material is controlled by the exterior incompressible fluid, for it offers no resistance whatever to the passage of the atom through it—in short, in so far as the motion of the atom is concerned, this fluid is a perfect void. ”

“ A small pipe opening just inside the shell of the cylinder is brought back to near the center, where it rises through a sort of neck and opens into an exterior casing. The pressure due to the velocity causes the skim milk to rise in this pipe and flow continuously out at the inner end. The cream is at the same time drawn off by a similar orifice made in the same neck and leading into a different chamber.
Centrifugal action is not the only way in which particles of different specific gravity can he separated from each other by motion only. ”

“ The portion of the machine destined to carry the tubes should be a metal disc, of sufficient weight to ensure good "flank" movement, continuing over a considerable period of time. In other words, the machine should run down very gradually and slowly after the motive power is removed, thus obviating any disturbance of the relative positions of particulate matter in the solution that is being centrifugalised. ”

“ In the centrifugal method carbon-bisulphide, or some other volatile agent, is admitted and is driven through the material by centrifugal force, when the necessary reactions take place, and is allowed to escape in the form of hydrocarbons. A machine differing only in slight particulars from the above is used for cleansing wool. ”

“ Perhaps the best example of such a filter is the cotton-wool plug which closes the mouth of a culture tube. Not only does ordinary diffusion take place through it, but if a tube plugged in the usual manner with cotton-wool is removed from the hot incubator, the temperature of the contained air rapidly falls to that of the laboratory, and a partial vacuum is formed; air passes into the tube, through the cotton-wool plug, to restore the equilibrium, and, so long as the plug remains dry, in a germ-free condition. ”

“ Finally, as heat increases, and more and more work is done, against the centripetal force of cohesion, most substances, and doubtless all if we could get heat enough, are converted from solids into fluids, and ultimately into gases, in which latter state the molecules have got altogether beyond the sphere of their mutual attraction, and tend to dart off indefinitely in the direction of their own proper centrifugal motions, unless confined, in which case they dart about, collide, rebound, and exercise pressure on the containing surface. ”

“ The consideration of centrifugal force proves, that if a body be observed to move in a curvilinear path, some efficient cause must exist which prevents it from flying off, and which compels it to revolve round the centre. If the body be connected with the centre by a thread, cord, or rod, then the effect of the centrifugal force is to give tension to the thread, cord, or rod. If an unyielding curved surface be placed on the convex side of the path, then the force will produce pressure on this102 surface. ”

“ We have strengthened the tubes of force passing from sphere to cylinder. The total flux emanating from the sphere has not altered, for that is strictly limited by the charge originally on the sphere, but whilst with a sphere free in space the flux is evenly distributed all round, we have, by bringing the cylinder near, and especially by discharging its positive electricity to earth, disturbed the symmetrical field of the sphere, making it much denser on its left half, and thus increased the inductive effect on the cylinder. ”

“ Occasionally filtration into a vacuum is practised, but more often, as in filter-presses, the liquid is forced under pressure, either hydrostatic or obtained from a force-pump or compressed air, into a series of chambers partitioned off by cloth, which arrests the solids, but permits the passage of the liquid portions. For separating liquids from solids of a fibrous or crystalline character “hydro-extractors” or “centrifugals” are frequently employed. ”

“ Centrifugal force, as applied in extractors, has opened up new industries and enlarged old ones, has lowered prices and added to our comforts, and centrifugal extractors may well command, as they do, the admiration of all as wonderful examples of the way in which this busy age economizes time. ”

“ If you take a spoonful of sand, salt, or dust, and drop it upon the top, it will be scattered in a circle, just as the atoms of the top would be, if they were free to separate, but not with the same force, because the atoms of the salt, &c., not being in an active state of rotation, would only be influenced by momentary contact with the rotating body. This tendency of the particles of a rotating body to fly outward from the centre, is called the centrifugal force. ”

“ That is dead matter, while our monkeys will be millions of living cells. The vacuum is created by simply screwing on this cap.”
“But not a perfect vacuum,” I interposed. “That is impossible.”
“Sufficiently near to eliminate the aerobic bacilli which flourish on oxygen, and the infinitesimal amount of that remaining in the cylinder is probably absorbed and transmuted by the surface capillaries and lungs, leaving simply carbon dioxide, neon, crypton, et cetera.”
I examined the cylinder nearest me with interest. A small dial was set into its cap. Lazaroff anticipated my question. ”

“ Thus the charge within the inner cylinder does not go on continually increasing; the cylinder settles down into a state of equilibrium in which the rate at which it gains negative electricity from the rays is equal to the rate at which it loses it by conduction through the air. If the inner cylinder has initially a positive charge it rapidly loses that charge and acquires a negative one; while if the initial charge is a negative one, the cylinder will leak if the initial negative potential is numerically greater than the equilibrium value. ”

“ Centrifugality originates only in a constrained manner or with reluctance, for the primary act always seeks the centre, and only moves towards the periphery, because it has no longer any place there. If centripetality be regarded as a force, then is centrifugality no force, but only centripetality itself retreating from the centre; even as cold and darkness are probably no particular forces in themselves, but only weaker degrees of heat or light.
153. Gravity is not motion simply, but motion unto a centre, unto rest. ”

“ The turbine blower and exhauster depend entirely upon centrifugal force for their power to compress or exhaust air or gas, etc. The use of centrifugal force makes this type of machine resemble the centrifugal water-pump, but radical differences in design have to be introduced, seeing that water is not compressible, whereas air is capable of compression, and alterations are also necessary, due to the great difference in specific gravity of the two substances. ”

“ It is evident that the amount of fluid which passes any fixed surface is measured by the number of unit tubes which cut it, and the direction in which the fluid passes is determined by that of its motion in the tubes. If the surface be a closed one, then any tube whose terminations lie on the same side of the surface must cross the surface as many times in the one direction as in the other, and therefore must carry as much fluid out of the surface as it carries in. A tube which begins within the surface and ends without it will carry out unity of fluid ”

“ Apparatus. All the apparatus of Exp. 126. Two simple cells (§ 275) , the plates of which should be of the same size, the same distance apart, and immersed in acid to the same extent in both. The acid in both should be of the same strength.
348. Directions. (A) Connect the two cells in opposition, so that no current will be generated by them, and so that the two [141] can be treated as a dead resistance. Do this by joining the two zinc plates by a wire with connectors, and use wires to connect the copper plates to the bridge like any other unknown resistance. ”

“ At this juncture, the negative accelerator must be immediately and rapidly rotated, inducing high disturbance of equilibrium between the transmitter and the disintegrator by triple negative evolution, with the result that a force of from five to ten, fifteen, twenty, and thirty thousand pounds to the square inch is evolved by the focalization of this triple negative stream on the disintegrating cell, or chamber, whether there be one, two, three, five, or ten drops of water enclosed within it. ”