ponents of this alloy being slightly electro-negative, and the other slightly electro-positive, with respect to cast iron. These results will also enable some advances to be made towards the solution of the important problem proposed by the author in his former report, viz.," the obtaining a mode of electro-chemical protection, such that while the metal (iron) shall be preserved, the protector shall not be acted on, and the protection of which shall be invariable."

Table X. exhibits especially the results of the action of sea water on cast iron, in the presence of copper and tin, or their alloys. It appears that copper and tin being both electro-negative with respect to cast iron, all their alloys increase or accelerate the rate of corrosion of cast iron in a solvent, though in very variable degrees; the maximum increase is produced by tin alone, thus indicating that this metal (contrary to what was previously believed) is more electro-negative to cast iron than copper. Hence the important practical deduction, that, where submerged, works in iron must be in contact with either alloy, viz., brass or gun metal; common brass, or copper and zinc, is much to be preferred. These experiments will also serve to demonstrate the fallacy of many of the patented so-called preservatives from oxidation, which are brought before the public with so much parade.

The author lastly proceeds to the subject of the specific gravity of cast iron, tables of which are added to the preceding. The specific gravities here recorded, were taken on equal sized cubes of the several cast irons cut by the planing machine, from bars of equal size, cast at the same temperature, in the same way, and cooled in equal times. Many of these results differ considerably from those given by Dr. Thompson and Mr. Fairbairn; which the author refers to the probability that those of Dr. Thompson were taken from pieces of the raw pig, and those of Mr. Fairbairn by weighing in air equal bulks, cut from the mass by the chisel and file, by which latter process the volume is liable to condensation. The experiments of Mr. Fairbairn and Mr. Eaton Hodgkinson, seem to shew that the ultimate strength of cast-iron is in the ratio of some function of the specific gravity dependant

upon the following conditions: viz. 1, the bulk of the casting; 2, the depth or head of metal under which the casting was made; 3, the temperature at which the iron was poured into the mould; and 4, the rate at which the casting was cooled.

Table XI.-All the irons experimented on, are arranged in classes, according to the character of the fracture; for which purpose the terms-1, silvery, 2, micaceous, 3, mottled, 4, bright grey, 5, dull grey, and 6, dark grey, have been adopted by the author as a sufficient basis on which to rest a uniform system of nomenclature for the physical characters of all cast irons, as recognisable by their fracture; and it is to be wished that experimenters in future would adopt this or some other uniform system of description, in place of the vague and often incorrect characteristics commonly attached to the appearance of the fracture of cast iron.

The twelfth and last table contains the results of a set of experiments on the important subject of the increase of density conferred on cast iron, by being cast under a considerable head of metal, the amount of which condensation had not been previously reduced to numbers. It shows this increase of density in large castings, for every 2 feet in depth, from 2 to 14 feet deep of metal.

A very rapid increase of density takes place at first, and below 4 feet in depth a nearly uniform increment of condensation.

The importance of these results is obvious; for, if the ultimate cohesion of castings is as some function of their specific gravity, the results of experiments in relation to strength, made on castings of different magnitudes, or cast under different heads, can only be made comparable by involving the variable specific gravities in the calculation.

List of Patents

Granted by the French Government from the 1st of January to the 31st of March, 1840.

PATENTS FOR FIFTEEN YEARS.

To Bourbon, represented in Paris by M. Perpigna, advocate of the French and Foreign Office for Patents, Rue Choiseul, No. 2, ter: for the preservation of vegetable substances, either ligneous or textile.

Clark, represented in Paris by M. Perpigna, advocate, for improvements in locomotives.

Coles, represented in Paris by M. Perpigna, advocate, for a new porte carbine.

Davies, of Manchester, represented in Paris by M. Perpigna, advocate, for improvements in looms.

Billet, represented in Paris by M. Perpigna, advocate, for improvements in mechanism for preserving carriages from being overturned.

Bourgeois, of Tangues, (Orne) represented in Paris by M. Perpigna, advocate, for improvements in locks.

Burnett, of London, represented in Paris, by M. Perpigna, advocate, for machinery for working wood.

Guyot-Duclos, represented in Paris by M. Perpigna, advocate, for improvements in the distillation of coal.

Perrot, of Rouen, for a press for lithographic and typographic impressions.

Few, of London, for improvements in locomotives.

Sorel, of Paris, for novel applications of iron preserved from oxidation.

Poole, of Paris, for improvements in weaving.

Royer, of Paris, for a furnace for working iron, and applicable to

the fusion of glass.

VOL. XVIII.

G

Wayte, of Basford, (England,) for improvements in wheels of

steam boats.

Sormani and Lagoutte, of Lacroix, for paddle wheels, applicable to steam navigation.

Cuningham, of Paris, for improvements in spinning machines. Bonifas-Cabane, and Paul, Jun., of Anduze, (Gard,) for an accelerating axletree.

Serveille, of Paris, for a new lock for carriages

Rampal and Gaulofret, of Paris, for an improvement in the manufacturing of soap.

Duquesne, of Valenciennes, for a machine for flatting and engraving glass.

Rommelnere, of Gand, (Belgium,) for a mode of manufacturing alum.

Demont and Follet, of Paris, for imitation stone for architectural ornaments.

Gandillot and Roy, of Paris, for windows in tabular iron.

Boutel, of the Batignolles, near Paris, for an improved water-closet. Borrodaile, of London, for a process for raising vessels, and other objects sunk in water.

Verry, of Paris, for a process for making bread.

Count de Baurepaire, and Loos, of Paris, for extracting sugar from cane and beetroot.

Lefaucheux, of Paris, for a new lock for carriages.
Moll, of Colmar, for a flour mill in cast-iron.

PATENTS FOR TEN YEARS.

To Trésel, of St. Quentin, represented in Paris by M. Perpigna, advocate of the French and Foreign Office for Patents, Rue Choiseul, 2 ter for a portable metrical measure.

Sudds, Adkins, and Barker, represented in Paris by M. Perpigna, advocate, for hydraulic wheels.

Amiot, represented in Paris by M. Perpigna, advocate, for an instrument for curling hair.

Amet, Conscience, and Morel, represented in Paris by M. Perpigna, advocate, for an improved plummer box.

Tachouzin, of Mont de Marsan, represented in Paris by M. Perpigna, advocate, for the manufacturing essence of turpentine. Dumotier and Baza, of Vadencourt, represented in Paris by M. Perpigna, advocate, for the manufacturing of shawls.

Dubois, represented in Paris by M. Perpigna, advocate, for surgical instruments.

Gallice, of Epernay, represented in Paris by M. Perpigna, advocate, for improvements in the preparation of sparkling wines. Ferrand, of Angers, represented in Paris by M. Perpigna, advocate, for an improved baking oven.

Gracien and Houet, of Hames, represented in Paris by M. Perpigna, advocate, for an improved extirpating instrument. Lecoffre, of Barenton, for a flatting machine.

Parpaite, Sen., of Messincourt, (Ardennes,) for improved looms. Geslot Menier, of Tours, for a new snuff box.

Hazard, of Paris, for a fountain stove.

Noakes, of Paris, for an improved paving.

Johnson, of London, for improved musical instruments.

Poole, of Paris, for improvements in stoves.

Poole, of Paris, for new frames for elastic stuffs.

Bracquemont and Falton, of Paris, for new trousers straps.

Parker, of London, for restoring of matters used for the clarifying of syrups.

Lawford-Ackland, of Paris, for metallic alloy for tubes, &c. Tripot, of Auteuil, near Paris, for painted paper, made by machinery.

Conty, of Abilly, (Indre & Loire,) for improvements in flour mills. De Grenier, of St. Omer, (Pas de Calais,) for a steam boiler.

Lucas Brothers, of Rheims, for a winder, fit for the spinning of worsted.

Aubril, of Paris, for powder for sharpening razors.
Sbodio, of Marseilles, for a new motive power.
Evangelista, of Angoulème, for an anti-febrile elixir.

Ferray and Co., of Paris, for improvements in mills.

Ferry, of Paris, for a new kind of spoons and forks, in gold, silver, &c.