Esters of polyhydric alcohols with polymerized and (or) oxidized fatty acids of more than eight carbon atoms, the esters containing at least one free hydroxyl group in the alcohol residue, are heated in the presence of an alkaline catalyst so as to convert some or all of the hydroxyl groups into ether linkages, with elimination of water. The starting material may be a simple ester of the type defined or a mixture of such esters, e.g. a mixture of mono-or di-glycerides, with or without tri-glycerides, of one or more polymerized and (or) oxidized fatty acids. Suitable polyhydric alcohols from which the starting materials may be derived are glycol, glycerol and sorbitol, but esters derived from polymerized and (or) oxidized fatty acids and condensed polyhydric alcohols, e.g. polyglycerol, may also be treated, with or without esters derived from uncondensed polyhydric alcohols. The catalyst may be an alkali-metal hydroxide, carbonate, bicarbonate or fatty acid salt. The products may be used as emulsifying agents, alone or with other emulsifying agents, e.g. in the production of emulsions of the water-in-oil type. In an example, soya bean oil is blown with air at 150 DEG C. and the product is heated with glycerol at 170-180 DEG C. in the presence of sodium acetate; a diglyceride of oxidized soya bean oil acids is so obtained and is heated to 250-260 DEG C. in the presence of sodium or potassium acetate or a sodium or potassium soap; the process may be effected in an inert atmosphere or in vacuo, with or without stirring. Specification 500,765, [Group IV], is referred to. The Specification as open to inspection under Sect. 91 states that the product of the example above may be used to produce an emulsion containing 65 per cent of water in tallow and that it may be used in admixture with other emulsifiers such as the monoglyceride of hardened earth-nut oil acid or diglycerol monostearate. The Specification refers also to the production of ethers by heating partial esters of polyhydric alcohols with unpolymerized or unoxidized saturated or unsaturated fatty acids, and includes the following examples: (2) glycerol monopalmitate or a monoglyceride produced from hardened ox-tallow or whale oil is heated to 250-260 DEG C. in the presence of sodium soap first in an atmosphere of carbon dioxide and then in vacuo, the product being useful as an emulsifier in margarine; (3) a mixture of oxidized soya bean oil monoglyceride and diglycerol monopalmitate is heated to 250-260 DEG C. in the presence of sodium soap to yield a product useful as an emulsifier in margarine and like emulsions; the monoglyceride used as starting material may be prepared by treating soya bean oil with air at about 170 DEG C. dissolving the product in fresh soya bean oil, and re-esterifying the mixture with glycerol in the presence of sodium acetate; (4) soya bean oil is polymerized at 290 DEG C. in vacuo and the product is re-esterified with glycerol at 190 DEG C. in the presence of sodium acetate; the monoglyceride so obtained is heated to 260-265 DEG C. to effect etherification and yield a product suitable for making an emulsion containing 65 per cent of water in soya bean oil; (5) soya bean oil polymerized as in example (4) is mixed with hardened whale oil and the mixture is re-esterified with glycerol at 190 DEG C. in vacuo; the monoglyceride mixture so obtained is heated to 265 DEG C. to effect etherification and yield a product useful in making margarine and like emulsions. This subject-matter does not appear in the Specification as accepted.ALSO:Esters of polyhydric alcohols with polymerized and/or oxidized fatty acids of more than eight carbon atoms, the esters containing at least one free hydroxyl group in the alcohol residue, are heated in the presence of an alkaline catalyst so as to convert some or all of the hydroxyl groups into ether linkages, with elimination of water. The starting material may be a simple ester of the type defined or a mixture of such esters, e.g. a mixture of mono-or di-glycerides, with or without tri-glycerides, of one or more polymerized and/or oxidized fatty acids. Suitable polyhydric alcohols from which the starting materials may be derived are glycol, glycerol and sorbitol, but esters derived from polymerized and/or oxidized fatty acids and condensed polyhydric alcohols, e.g. polyglycerol, may also be treated, with or without esters derived from uncondensed polyhydric alcohols. The catalyst may be an alkali-metal hydroxide, carbonate, bicarbonate or fatty-acid salt. The products may be used as emulsifying agents, alone or with other emulsifying agents, e.g. in the production of emulsions of the water-in-oil type and in the manufacture of cosmetics. In an example, soya bean oil is blown with air at 150 DEG C. and the product is heated with glycerol at 170-180 DEG C. in the presence of sodium acetate; a diglyceride of oxidized soya bean oil acids is so obtained and is heated to 250-260 DEG C. in the presence of sodium or potassium acetate or a sodium or potassium soap; the process may be effected in an inert atmosphere or in vacuo, with or without stirring. Specification 500,765 is referred to. The Specification as open to inspection under Sect. 91 states that the product of the example above may be used to produce an emulsion containing 65 per cent of water in tallow and that it may be used in admixture with other emulsifiers such as the monoglyceride of hardened earth-nut oil acid or diglycerol mono-stearate. The Specification refers also to the production of ethers by heating partial esters of polyhydric alcohols with unpolymerized or unoxidized saturated or unsaturated fatty acids, and includes the following examples: (2) glycerol monopalmitate or a monoglyceride produced from hardened ox-tallow or whale oil is heated to 250-260 DEG C. in the presence of sodium soap first in an atmosphere of carbon dioxide and then in vacuo, the product being useful as an emulsifier in margarine; (3) a mixture of oxidized soya bean oil monoglyceride and diglycerol monopalmitate is heated to 250-260 DEG C. in the presence of sodium soap to yield a product useful as an emulsifier in margarine and like emulsions; the monoglyceride used as starting material may be prepared by treating soya bean oil with air at about 170 DEG C., dissolving the product in fresh soya bean oil, and re-esterifying the mixture with glycerol in the presence of sodium acetate; (4) soya bean oil is polymerized at 290 DEG C. in vacuo and the product is re-esterified with glycerol at 190 DEG C. in the presence of sodium acetate; the monoglyceride so obtained is heated to 260-265 DEG C. to effect etherification and yield a product suitable for making an emulsion containing 65 per cent of water in soya bean oil; the product may also be used for producing baking emulsions in which 60 per cent of an aqueous phase, which may contain sugar, milk powder or like substances, is emulsified in a mixture of solid and liquid fats; further, the product may be used for the production of cosmetic creams of the water-in-oil type, a specified composition containing earth-nut oil 20, beeswax 10, paraffin oil 7.5, emulsifier 2.5 and water 60 per cent; (5) soya bean oil polymerized as in example (4) is mixed with hardened whale oil and the mixture is re-esterified with glycerol at 190 DEG C. in vacuo; the monoglyceride mixture so obtained is heated to 265 DEG C. to effect etherification and yield a product useful in making margarine and like emulsions and cosmetic creams. This subject-matter does not appear in the Specification as accepted.ALSO:In producing emulsions of water in fat, for baking purposes, the emulsifying agent is obtained by heating an ester of a polyhydric alcohol with a polymerized and (or) oxidized fatty acid of more than eight carbon atoms, the ester containing at least one free hydroxyl group in the alcohol residue, in the presence of an alkaline catalyst so as to convert some or all of the hydroxyl groups into ether linkages, with elimination of water. The starting material may be a simple ester of the type defined or a mixture of such esters, e.g. a mixture of mono- or di-glycerides, with or without tri-glycerides, of one or more polymerized and (or) oxidized fatty acids. Suitable polyhydric alcohols from which the starting materials may be derived are glycol, glycerol and sorbitol, but esters derived from polymerized and (or) oxidized fatty acids and condensed polyhydric alcohols, e.g. polyglycerol, may also be treated, with or without esters derived from uncondensed polyhydric alcohols. In an example, soya bean oil is blown with air at 150 DEG C. and the product is heated with glycerol at 170 - 180 DEG C. in the presence of sodium acetate; a diglyceride of oxidised soya bean oil acids is so obtained and is heated to 250 - 260 DEG C. in the presence of sodium or potassium acetate or a sodium or potassium soap; the process may be effected in an inert atmosphere or in vacuo, with or without stirring. Specification 500,765, [Group IV], is referred to. The Specification as open to inspection under Sect. 91 includes the following examples:- (2) glycerol monopalmitate or a monoglyceride produced from hardened ox-tallow or whale oil is heated to 250 - 260 DEG C. in the presence of sodium soap first in an atmosphere of carbon dioxide and then in vacuo, the product being useful as an emulsifier in margarine; (3) a mixture of oxidized soya bean oil monoglyceride and diglycerol monopalmitate is heated to 250-260 DEG C. in the presence of sodium soap to yield a product useful as an emulsifier in margarine and like emulsions; (4) soya bean oil is polymerized at 290 DEG C. in vacuo and the product is re-esterified with glycol at 190 DEG C. in the presence of sodium acetate; the monoglyceride so obtained is heated to 260-265 DEG C. to effect etherif