168 History of Mechanical Inventions, atid 



oxygen at common temperatures, or even when artificially heated. It is 

 formed out of many metals. It does not increase the hardness of the ar- 

 ticle to which it is applied, nor does it efface the finest lines on the sur- 

 face. It does not injure the temper of knives. Four ounces of this com- 

 position is sufficient to cover an iron bedstead; and twelve ounces are valued 

 at a dollar and 50 cents. 



A company is already formed at Bologna with a capital of 1 00,000 dollars 

 for coating iron work, and they are now drawing out plates which can be 

 united to one another by heat, without any injury to the coating. — Frank- 

 tin Journal, 



4. Composition for washing in Sea Water, By Edward Heard^ Chemist, 



liOndon. 

 This composition, which is secured by patent, is thus made. Take a high- 

 ly concentrated solution of the alkalis, soda, or potash, with an equal weight 

 of any earthy base, (China-clay or porcelain earth is best.) These mate- 

 rials being mixed together are to be ground in a mill in the same way as 

 white lead is ground, and this will produce a thick paste, one pound of 

 which is sufficient to soften four gallons of sea water.— See Newton's 

 Journal, Nov. 1827, p. 151. 



5. Process for giving Statues and! Medals the appearance of Bronze, 

 Take two drachms of sal-ammoniac, half a drachm of salt of sorrel, and 

 dissolve them in half a pint of white vinegar ; after having well-cleaned 

 the metal from verdigrease, moisten a brush by dipping it softly into this 

 solution, then rub it continually on the same place till the colour becomes 

 dry and assumes the tone or depth of shade desired. In order that the 

 drying may be more rapid, this operation is to be performed in the sun- 

 shine, or by the heat of a stove. The oftener it is repeated on the same 

 place the deeper proportionably will be the colour of the bronze. This 

 process is used by M. Jacob of Paris. — Journal des Connaiss. Utiles. 



6. Account of an improvement in the construction of Bedsteads, Sofas, ^c. 

 This improvement, communicated to Mr Perkins by a foreigner, is very 

 simple and effective. The object of it is to keep the canvass bottom or 

 sacking of a bed always in a proper state of tension. This is effected by 

 making the two horizontal bars or rails to which the canvass is nailed, turn 

 a little round their axis by means of a lever. They are then held in this 

 position, which of course stretches the canvass, by a click and ratchet 

 wheel, which has also the effect of keeping the joints of the rails and posts 

 firmly together. — See Newton's Journal, July 1827, p. 256. 



7. Account of new Bricks for building both cylindrical and curved Chim," 



nies. By Mr J. W. Hiort, Architect. 



This contrivance is a very ingenious one, and at the same time highly 



useful. The patent bricks are of a wedge form, as their upper and lower 



sur&ces are not parallel, and one of their sides has the curve of a quarter of 



