_Manganese Oxalate._--A writer in the _Moniteur de Produits Chimiques_ draws attention to the properties possessed by manganese oxalate as a drier. This salt has hitherto not had any important industrial uses, but it can be readily prepared in a state of purity from the native carbonate by the action of oxalic acid; the author is of the opinion that it will be found of use for this purpose. If prepared from carbonate free from iron and lime, it can be obtained as a fine crystalline white powder, and two-fifths per cent. suffices to bring about the change. The oxalate is resolved by heat into manganese oxide, carbonic acid and carbon monoxide, and in the presence of fatty acids the manganese oxide formed combines with them, the decomposition taking place at about 130°. The operation is carried out by mixing in a mortar the oxalate with two or three times its weight of oil, and then adding the mixture to the main portion of the oil. The heat should be applied gradually, and the decomposition is known to be complete when there is no further evolution of gas. The boiled oil, under this treatment, preserves its limpidity and also remains colourless. Manganese oxalate has the advantage over oxide of lead, which is commonly employed for this purpose, in causing the oil to remain transparent when exposed to sulphur vapours. Manganese acetate has also been used, but it likewise causes a darkening in the colour of the oil, and the nitrate is dangerous owing to the possible action of nitric acid on the fats present in the oil. Manganese borate appears to be next in value to the oxalate as an oil drier. In a paper recently read before the Society of Arts, Prof. Hartley remarked that paint, such as is used for ordinary purposes, is essentially composed of three materials, without taking into account the coloured pigments. (1) White lead, or sublimed zinc-white. (2) An oil, generally linseed or poppy oil, which is ground up with the white lead or zinc-white until it becomes a soft paste. This is mixed with variable preparations of linseed oil and spirit of turpentine. (3) A substance called dryers, or siccative materials; it may be linseed oil in which litharge is dissolved, or it may be linseed oil containing a compound of manganese. Paint owes to the dryers its property of drying more rapidly than it would do without it; and it is considered indispensable in buildings in all cases where paint applied to wood, stone, or metal, would not be quite dry in 48 hours, or at most in 72 hours, after the first application. The first question which requires an answer is, what chemical process takes place when a paint dries.