Abstract: m-Xylene is difficult to separate from o-xylene by conventional distillation or rectification because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is dimethylsulfoxide or a mixture of it with certain high boiling organic compounds. Typical examples of effective agents are: dimethylsulfoxide; dimethylsulfoxide and 1,4-butanediol; dimethylsulfoxide, nitrobenzene and diethylene glycol.

Abstract: A hot-line device for telephone sets includes a logic AND gate circuit serving as a central unit with its output to be electrically connected to a control circuit through the keyboard of a telephone set, and its inputs respectively coupled with a hot-line triggering circuit, a dial-tone detection circuit and a ringing detection and delay circuit separately disposed in the telephone set for automatically effecting dialing operation during an emergency situation. Alternatively, the logic AND gate circuit can be replaced with a microprocessor for performing automatic dialing operation through a predetermined program.

Abstract: A switching control apparatus for intercom-telephone sets includes a switching control circuit and a surge protection circuit electrically coupled with a talking circuit for increasing the reliability of the intercom-telephone operation, reducing the cost of manufacturing the product and protecting the intercom-telephone sets against high voltage surges which may damage the intercom-telephone sets during electrical storms.

Abstract: m-Xylene is difficult to separate from o-xylene by conventional rectification or distillation because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is ethyl-2-hydroxybenzoate; methyl benzoate plus benzophenone; methyl benzoate, butyl benzoate and dimethylsulfoxide.

Abstract: Impure formic acid cannot be completely removed from formic acid-water-impurity mixtures by distillation because of the presence of the maximum azeotrope between formic acid and water. Formic acid can be readily removed from mixtures containing it, water and impurities of the ether, ester, ketone or diketone type by using extractive distillation in which the extractive agent is a higher boiling oxygenated, nitrogenous or sulfur containing organic compound or a mixture of these. Examples of effective agents are adiponitrile; sulfolane and salicyclic acid; dimethylformamide, N,N-dimethylacetamide and ethylene glycol ethyl ether acetate.

Abstract: Isobutyl acetate cannot be completely removed from isobutyl acetate - isobutanol - water mixtures by distillation because of the presence of the minimum ternary axeotrope. Isobutyl acetate can be readily removed from mixtures containing it, isobutanol and water by using extractive distillation in which the extractive distillation agent is a higher boiling oxygenated, nitrogenous and/or sulfur containing organic compound or a mixture of these. Typical examples of effective agents are dimethylsulfoxide; dimethylsulfoxide and dimethylformamide; dimethylsulfoxide, dimethylformamide and N,N-dimethylacetamide.

Abstract: 2-Butyl acetate cannot be completely removed from 2-butyl acetate-2-butanol-water mixtures by distillation because of the presence of the minimum ternary azeotrope. 2-butyl acetate can be readily removed from mixtures containing it, 2-butanol and water by using extractive distillation in which the extractive distillation agent is a higher boiling oxygenated, nitrogenous and/or sulfur containing organic compound or a mixture of these. Typical examples of effective agents are N,N-dimethylacetamide; dimethylformamide and ethylene glycol; acetamide, dimethylsulfoxide and ethylene glycol.

Abstract: Isopropyl acetate cannot be completely removed from isopropyl acetate - isopropanol - water mixtures by distillation because of the presence of the minimum ternary azeotrope. Isopropyl acetate can be readily removed from mixtures containing it, isopropanol and water by using extractive distillation in which the extractive agent is a higher boiling oxygenated or nitrogenous organic compound or a mixture of these. Typical examples of effective agents are diethanolamine; ethanolamine and N-methyl pyrrolidone; triethanolamine and N-methyl pyrrolidone.

Abstract: n-Amyl acetate cannot be completely removed from n-amyl acetate - n-amyl alcohol - water mixtures by distillation because of the presence of the minimum ternary azeotrope. n-Amyl acetate can be readily removed from mixtures containing it, n-amyl alcohol and water by using extractive distillation in which the extractive distillation agent is a higher boiling organic compound or a mixture of these. Typical examples of effective agents are ethylene glycol; propylene glycol and dimethylsulfoxide; 1,3-butanediol, dimethylformamide and acetamide.

Abstract: m-Xylene is difficult to separate from o-xylene by conventional rectification or distillation because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is dimethylformamide; dimethylformamide and 1,4-butanediol; dimethylformamide, adiponitrile and dihexyl phthalate.

Abstract: m-Xylene is difficult to separate from o-xylene by conventional distillation or rectification because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is adiponitrile or a mixture of it with certain high boiling organic compounds. Typical examples of effective agents are: adiponitrile; adiponitrile and 1,4-butanediol; adiponitrile, ethylene carbonate and benzyl alcohol.

Abstract: n-Propyl acetate cannot be completely removed from n-propyl acetate - n-propanol - water mixtures by distillation because of the presence of the minimum ternary azeotrope. n-Propyl acetate can be readily removed from mixtures containing it, n-propanol and water by using extractive distillation in which the extractive distillation agent is a higher boiling oxygenated or nitrogenous organic compound or a mixture of these. Typical examples of effective agents are N-methylpyrrolidone; triethanolamine; N-methylpyrrolidone and ethylene glycol.

Abstract: m-Xylene is difficult to separate from o-xylene by conventional distillation or rectification because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is a mixture polychloro aromatic compounds. Typical examples of effective agents are 2,3,4,6-tetrachlorophenol and p-dichlorobenzene; dimethyltetrachloroterephthalate, 2,3,4,6-tetrachlorophenol and 1,2,4,5-tetrachlorobenzene; 2,4,5-trichlorophenol, benzene hexachloride, o-dichlorobenzene and dioctyl phthalate.

Abstract: n-Amyl acetate cannot be completely removed from n-amyl acetate - n-amyl alcohol - water mixtures by distillation because of the presence of the minimum ternary azeotrope. n-Amyl acetate can be readily removed from mixtures containing it, n-amyl alcohol and water by using extractive distillation in which the extractive distillation agent is a higher boiling organic compound or a mixture of these. Typical examples of effective agents are dimethylsulfoxide; N,N-dimethylacetamide and dimethylsulfoxide; dimethylformamide, N,N-dimethylacetamide and acetamide.

Abstract: Propanoic acid cannot be completely removed from propanoic-water mixtures by distillation because of the presence of the minimum azeotrope. Propanoic acid can be readily removed from mixtures containing it and water by using extractive distillation in which the extractive distillation agent is an acid amide. Typical examples of effective agents are acetamide; dimethylformamide and methyl glutaronitrile; formamide, adiponitrile and N,N-dimethylacetamide.

Abstract: Isopropyl ether cannot be completely removed from isopropyl ether--isopropanol--water mixtures by distillation because of the presence of the minimum ternary azeotrope. Isopropyl ether can be readily removed from mixtures containing it, isopropanol and water by using extractive distillation in which the extractive distillation agent is a higher boiling glycol, glycol ether or a mixture of them. Typical examples of effective agents are ethylene glycol, propylene glycol, diethylene glycol diethyl ether plus propylene glycol ethyl ether.

Abstract: Water cannot be completely removed from ethanol by distillation because of the presence of the minimum azeotrope. Ethanol can be readily dehydrated by using extractive distillation in which the water is removed as overhead product and the ethanol and extractive agent as bottoms and subsequently separated by conventional rectification. Typical examples of suitable extractive agents are hexahydrophthalic anhydride; methyl tetrahydrophthalic anhydride and pentanol-1; trimellitic anhydride, ethyl salicylate and resorcinol.

Abstract: An automatic telephone silencer and volume controller having a microprocessor for storing time and volume information and for timely controlling the sound characteristics of a telephone ringer in accordance with the time and volume information stored. The time and volume information may be entered into the microprocessor by a suitable keyboard. Each time entry has associated with it a volume entry so that the telephone will ring at the prescribed volume from that time until the time denoted by the next time entry.

Abstract: Formic acid cannot be completely removed from formic acid - water mixtures by distillation because of the presence of the maximum azeotrope. Formic acid can be readily removed from mixtures containing it and water by using extractive distillation in which the extractive distillation agent is a sulfone. Typical examples of effective agents are thiophan sulfone; dimethyl sulfone and adiponitrile; phenyl sulfone, adiponitrile and acetophenone.

Abstract: Isobutyl acetate cannot be completely removed from isobutyl acetate--isobutanol--water mixtures by distillation because of the presence of the minimum ternary azeotrope. Isobutyl acetate can be readily removed from mixtures containing it, isobutanol and water by using extractive distillation in which the extractive distillation agent is a higher boiling oxygenated, nitrogenous and/or sulfur containing organic compound or a mixture of these. Typical examples of effective agents are N,N-dimethylacetamide; dimethylformamide and dimethylsulfoxide; acetamide, dimethylformamide and dipropylene glycol.