Paper drying

The oxime is freely soluble in water and in most organic liquids. Recrystallise the crude dry product from a minimum of 60-80 petrol or (less suitably) cyclohexane for this purpose first determine approximately, by means of a small-scale test-tube experiment, the minimum proportion of the hot solvent required to dissolve the oxime from about 0-5 g. of the crude material. Then place the bulk of the crude product in a small (100 ml.) round-bottomed or conical flask fitted with a reflux water-condenser, add the required amount of the solvent and boil the mixture on a water-bath. Then turn out the gas, and quickly filter the hot mixture through a fluted filter-paper into a conical flask the sodium chloride remains on the filter, whilst the filtrate on cooling in ice-water deposits the acetoxime as colourless crystals. These, when filtered anddried (either by pressing between drying-paper or by placing in an atmospheric desiccator) have m.p. 60 . Acetoxime sublimes rather readily when exposed to the air, and rapidly when warmed or when placed in a vacuum. Hence the necessity for an atmospheric desiccator for drying purposes. 

For the latter purpose, dissolve the crystals in hot ethanol, and then add water drop by drop to the well-stirred solution until a line emulsion just appears then add more ethanol, also drop by drop, until the emulsion just redissolves. ow allow the solution to cool spontaneousK if the emulsion reappears, add a few drops of ethanol from time to time in order to keep the solution clear. Finally the o-nitrophenol separates in crystals, and the well-stirred mixture may now be cooled in ieewvater until crystallisation is complete. Filter, drain and diy either in an atmospheric desiccator, or by pressing between drying-paper. 

Fit a 750 ml, bolt-head flask (also by a rubber stopper) to a reflux water-condenser closed at the top by a calcium chloride tube ensure that flask and condenser are quite dr). Place 150 ml. of the dried ethyl acetate in the flask and add 15 g. of sodium. The sodium for this purpose should preferably be added in the form of wire directly from a sodium press (Fig. 55, p. 82) alternatively the sodium may be added as thin slices, but in this case each slice should be quickly pressed between drying-paper before being added to the acetate to remove the wet film which may have formed during the weighing and cutting of the metal. 

Fit securely to the lower end of the condenser (as a receiver) a Buchner flask, the side-tube carrying a piece of rubber tubing which falls well below the level of the bench. Steam-distil the ethereal mixture for about 30 minutes discard the distillate, which contains the ether, possibly a trace of unchanged ethyl benzoate, and also any biphenyl, CeHs CgHs, which has been formed. The residue in the flask contains the triphenyl carbinol, which solidifies when the liquid is cooled. Filter this residual product at the pump, wash the triphenyl-carbinol thoroughly with water, drain, and then dry by pressing between several layers of thick drying-paper. Yield of crude dry product, 8 g. The triphenyl-carbinol can be recrystallised from methylated spirit (yield, 6 g.), or, if quite dry, from benzene, and so obtained as colourless crystals, m.p. 162. ... 

Now roll up the Carius tube (while still in a vertical position) in a strip of ordinary thick drying paper, and then place it in the heavy iron protector tube if the Carius tube is too short and tends to disappear within the iron tube, a short section of old glass tubing should first be placed in the iron tube so that the capillary of the Carius tube just projects. The function of the paper is to protect the Carius tubing from being scratched, and also (more important) to prevent the local overheating which would otherwise occur at places where the Carius tube is in direct contact with the iron tube. The sealed tube, throughout its manipulation, should be left as nearly vertical as possible, so that the contents do not leave the rounded end. 

In order to dry the crystals, the Buchner funnel is inverted over two or three thicknesses of drying paper (i.e., coarse-grained, smooth surfaced Alter paper) resting upon a pad of newspaper, and the crystalline cake is removed with the aid of a clean spatula several sheets of drying paper are placed on top and the crystals are pressed flrmly. If the sheets become too soiled by the mother liquor absorbed, the crystals should be transferred to fresh paper. The disadvantage of this method of rapid drying is that the recrystallised product is liable to become contaminated with the Alter paper flbre. 

Another method, which is especiafly suitable for low melting point solids or solids which decompose at low temperatures, is to place the material on a porous plate or pad of drying paper, and to cover the latter with another sheet of Alter paper perforated with a number of holes or with a large clock glass or sheet of glass supported upon corks. The air drying is continued until the solvent has been completely eliminated. 

Place 125 ml. of concentrated ammonia solution (sp. gr. 0-88) in a 600 ml. beaker and surround the latter with crushed ice. Stir the ammonia solution mechanically, and introduce the n-caproyl chloride slowly by means of a suitably supported separatory funnel with bent stem. The rate of addition must be adjusted so that no white fumes are lost. The amide separates immediately. Allow to stand in the ice water for 15 minutes after all the acid chloride has been introduced. Filter oflF the amide at the pump use the flltrate to assist the transfer of any amide remaining in the beaker to the Alter (2). Spread the amide on sheets of Alter or drying paper to dry in the air. The crude n-capro-amide (30 g.) has m.p. 98-99° and is sufficiently pure for conversion into the nitrile (Section 111,112) (3). Recrystallise a small quantity of the amide by dissolving it in the minimum volume of hot water and allowing the solution to cool dry on filter paper in the air. Pure n-caproamide has m.p. 100°. 

Processes. The most common method for the appHcation of chemicals to the surface of a paper web is by a size press. In the size press, dry paper, which usually is sized to prevent excess water and chemical penetration, is passed through a flooded nip or pond, and a solution or dispersion of the functional chemical contacts both sides of the paper. Excess Hquid is squeezed out in a press and the paper is redried. 

Ink particle redeposition on cellulose fibers can reduce deinked paper brightness. Should larger ink particles redeposit on fibers, visible ink specks may result. Sodium siUcate is often added to the pulper to act as a dispersant and reduce this redeposition (6,14). Up to 5% based on dry paper weight may... 

The quality of the air supply directly affects the output, efficiency and life of the engine. The requirement of the induction system must therefore be to supply the engine with clean dry air close to ambient temperature conditions. Oil bath or dry (paper element) filters are adequate for low dust concentration conditions. However, as the dust burden of the air increases, centrifugal pre-cleaners become... 

Slides with only a thin film can be fixed by being immersed in absolute methyl or ethyl alcohol for 1 min and allowed to air dry. If the thick film is on one end of the slide and the thin film is on the other end, the thin film is fixed by a brief flooding or by immersion in alcohol and allowed to air dry, while the thick film is protected from alcohol or alcohol fumes. In a well-ventilated area, the slide may be dried vertically with the thick film up or horizontally after the thick film is covered with a dry paper towel. 

A Petri dish containing bacterial colonies is blotted with nitrocellulose paper. This transfers a large portion of each colony to the paper, which is saturated with a solution that lyses (breaks open) the cells. The DNA of the lysed colonies is denatured with alkali. The nitrocellulose paper is neutralized, washed, and the paper either baked in an oven or treated with ultraviolet light to immobilize the denatured DNA. The DNA on the paper is hybridized with the labeled probe of interest, and the excess label is washed off. The dried paper is exposed to photographic film and the film developed. The exposed spots on the film can be matched with the colonies on the master plate and colonies picked off for further study. 

MATERIALS Two tin can lids or similar pieces of metal, dry paper, battery, electric wire, electric blasting cap. 

Make a sandwich of the lids, with a piece of dry paper in between completely separating the lids. The lid with the nail holes may be on top or bottom, but the pips must point in toward the paper, as shown in Figure 6. 

Kobayashi, M. Vial variance of the sublimation rate in shelf freeze-drying. Paper 312. International Institute of Refrigeration (Montreal 1991)... 

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