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On the amount of caffeine in coffee-beans
.Destruction of Insects.
859
like one on glass, and of a beautiful sepia tint. Nothing prevents the use of chloride of gold if that is desired. The washing may be done in a quarter of an hour, in place of lasting from 12 to 24 hours, and the proof is of admirable transparence, the paper also keeping all its white-
ness.--Comptes tlendus de l'Aead, des Sciences de Paris.
On the Amount of Caffeine in Coffee-beans* By Prof. A. VOO•L, Jr. The method hitherto employed for the extraction of caffeine from coffee beans or tea leaves, is both complicated and uncertain. It consists in extracting the coffee beans with water, precipitating the tannic acid from the solution by lead salts, and evaporating only the solution freed from lead for crystallization. This method is exceedingly inconvenient, and this is probably the principal reason why the statements as to the amount of caffeine in coffee differ so much from each other. The following method appears to the author to be much simpler and to lead to more accurate results. It is founded on the treatment of powdered coffee beans with commercial benzole. This extracts two constituents from the eoffee--oilof coffee and caffeine. After the evaporation of the benzole, these two substances may be easily separated from each other by agitation with hot water, in which the caffeine dissolves, whilst the oil floats on the surface and may be skimmed off. The caffeine is. obtained by the evaporation of the aqueous solution, in very beautiful crystals, which may be sublimed. The whole of the benzole may be recovered, by distilling it in a retort, after it has stood about a week upon the coffee beans. The residue in the retort is the oil of coffee and caffeine, which may be separated as above by agitation with water, or by treatment with ether, which dissolves the oil and leaves the caffeine in crystals. By this method oil of coffee and caffeine might be obtained as subsidiary products in benzole manufactories.--I(unst-und ~ewerbeblatt fi~r Bayern, 1858. * From the London Chemical Gazett% No. 377.
Destruction of Insects. M. Millet Brul~ exhibited before the Imperial Central Horticultural Society, of Paris, the efficacy of the powdered proto-sulphuret of iron, (which has been before used for the preservation of timber,) in destroying noxious and annoying insects. The powder may be strewed over the ground around the roots of the tree, or fixed on the surface of a collar surrounding the stem : no insect will pass it, or if they attempt it they are immediately killed. The proto-sulphuret of iron (black pyrites,) occurs as a mineral in various parts of France and Germany, and is manufactured for the purpose of developing sulphuretted hydrogen, which is undoubtedly the effective agent in destroying the vermin.--Cosmos.
859
like one on glass, and of a beautiful sepia tint. Nothing prevents the use of chloride of gold if that is desired. The washing may be done in a quarter of an hour, in place of lasting from 12 to 24 hours, and the proof is of admirable transparence, the paper also keeping all its white-
ness.--Comptes tlendus de l'Aead, des Sciences de Paris.
On the Amount of Caffeine in Coffee-beans* By Prof. A. VOO•L, Jr. The method hitherto employed for the extraction of caffeine from coffee beans or tea leaves, is both complicated and uncertain. It consists in extracting the coffee beans with water, precipitating the tannic acid from the solution by lead salts, and evaporating only the solution freed from lead for crystallization. This method is exceedingly inconvenient, and this is probably the principal reason why the statements as to the amount of caffeine in coffee differ so much from each other. The following method appears to the author to be much simpler and to lead to more accurate results. It is founded on the treatment of powdered coffee beans with commercial benzole. This extracts two constituents from the eoffee--oilof coffee and caffeine. After the evaporation of the benzole, these two substances may be easily separated from each other by agitation with hot water, in which the caffeine dissolves, whilst the oil floats on the surface and may be skimmed off. The caffeine is. obtained by the evaporation of the aqueous solution, in very beautiful crystals, which may be sublimed. The whole of the benzole may be recovered, by distilling it in a retort, after it has stood about a week upon the coffee beans. The residue in the retort is the oil of coffee and caffeine, which may be separated as above by agitation with water, or by treatment with ether, which dissolves the oil and leaves the caffeine in crystals. By this method oil of coffee and caffeine might be obtained as subsidiary products in benzole manufactories.--I(unst-und ~ewerbeblatt fi~r Bayern, 1858. * From the London Chemical Gazett% No. 377.
Destruction of Insects. M. Millet Brul~ exhibited before the Imperial Central Horticultural Society, of Paris, the efficacy of the powdered proto-sulphuret of iron, (which has been before used for the preservation of timber,) in destroying noxious and annoying insects. The powder may be strewed over the ground around the roots of the tree, or fixed on the surface of a collar surrounding the stem : no insect will pass it, or if they attempt it they are immediately killed. The proto-sulphuret of iron (black pyrites,) occurs as a mineral in various parts of France and Germany, and is manufactured for the purpose of developing sulphuretted hydrogen, which is undoubtedly the effective agent in destroying the vermin.--Cosmos.