PAPER.

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M. Laurot, a Parisian chemist, finds that colza oil (analogous to rapeseed oil) maybe tested for sophistication with cheaper vegetable oils by the increase of densitywhich it therefrom acquires, and which becomes very evident when the several oilsare heated to the same pitch. The instrument, which he calls an oleometer, is merelya hydrometer, with a very slender stem. He plunges' it into a tin cylinder, filled withthe oil, and sets this cylinder in another containing boiling water. His oleometer isso graduated as to sink to zero in pure colza oil so heated; and he finds that it stopsat 210° in linseed oil, at 124° in poppy-seed oil, at 83° in fish oil, and at 136° in hemp-seed oil—all of the same temperature. By the increase of density, therefore, or theascent of the stem of the hydrometer in any kind of colza oil, he can infer its degreeof adulteration.

The presence of a fish oil in a vegetable oil is readily ascertained by agitation with alittle chlorine gas, which blackens the fish oil, but has little or no effect upon thevegetable oil.

I find that lard oil, and also hogs’ lard, are not at all darkened by chlorine.

A specific gravity, bottle or globe, having a capillary tube-stopper, would make anexcellent oleometer, on the above principle. The vessel should be filled with the oil,and exposed to the heat of boiling water, or steam at 212°, till it acquires that tem-perature, and then weighed. The vessel with the pure colza oil will weigh severalgrains less than with the other oils similarly treated. Such an instrument would serveto detect the smallest adulterations of sperm oil. Its specific gravity at 60° whenpure is only 0-875; that of southern whale oil is 0922, or 0925; and hence theirmixture will give a specific gravity intermediate, according to the proportion in themixture. Thus I have been enabled to detect sperm oil in pretended lard oil, in myexamination of oils for the customs.

OPIUM. Imported for consumption in 1839, 41,632 lbs.; in 1840, 46,736; duty,is. per lb.

P.

PAPER. The construction of wire-web cylinders for paper-making machines, andthe combination of two such cylinders in one machine, by the use of which two distinctthicknesses of paper pulp are obtained, and applied face-wise, to form one thick sheet,were made the subject of a patent under the name of John Donkin. Two cylindersare so placed in a vat that their circumferences are nearly in contact, and by beingturned in opposite directions, they bring two sheets of paper pulp into contact, and in-corporate them into one, by what is technically termed coaching.

An extensive patent for improvements in the manufacture of paper was granted toCharles Edward Amos in 1840. These consist, first, in gradually lowering the roll ofthe engine in which the rags are prepared and converted into pulp; secondly, in a modeof regulating the supply of pulp to the paper-making machine, in order to produce papersof any required thickness; thirdly, in an improved sifter or strainer through which thepulp is passed for clearing it of knobs and lumps; fourthly, in certain modifications ofthe parts of the machine in which the pulp is deposited and moulded into continuouslengths of paper; fifthly, in an improved method of heating the cylinders of the dryingapparatus ; and, sixthly, in improvements of the machinery for cutting the paper intosheets of any required dimensions. The details of these ingenious contrivances, illus-trated with engravings, are given in Newton’s Journal, xx., p. 153., C. S.

Henry Crossley purposes to manufacture paper from waste tan, and spent hops—with what success I have not heard. Joseph Hughes gives a higher finish to the longweb of paper by friction between two cylinders, the one of which moves much quickerthan the other, both being covered with felt or not, at pleasure.

Mr. John Dickinson , the eminent paper manufacturer, obtained a patent in 1840lor a new mode of sizing paper continuously, in an air-tight vessel (partly exhaustedof air), by unwinding a scroll of dried paper from a reel, and conducting it throughheated size; then, after pressing out the superfluous size, winding the paper on to an-other reel.

A longitudinal section of the apparatus employed for this purpose is representedfig. 109; where a is the air-tight vessel; b, the reel upon which the paper to be sizedis wound; whence it proceeds beneath the guide-roller c, and through the warm sizeto another guide-roller d. It thence ascends between the press-rolls, e,f (by whose^evolution the paper is drawn from the reel b), and is wound upon the reel g. A float* is suspended from the cross-bar i, of the vessel a, for the purpose of diminishing thesurface of size exposed to evaporation; and beneath the bottom of the vessel is an