MISCELLANEOUS. 



69 



Method of preserving animal substan- 

 ces. — A solution of muriate of soda, or 

 common salt a little below saturation 

 will preserve animal substances for an in- 

 definite period at all the temperatures of 

 our atmosphere. — same. 



Improvements in axle trees. — The im- 

 provement consists in making the lower 

 part (say from one third to a half) of the 

 axle a segment of the same diameter as the 

 opening in the nave of the wheel, and the 

 upper portion of the axle a segment of a 

 circle, say half an inch less in diameter than 

 the lower; the shoulder or offset connecting 

 these two portions may be made to descend 

 at an angle of about one degree which will 

 permit the oil or other lubricating sub- 

 stance to descend and furnish a constant 

 supply to the rubbing surfaces, both of 

 the wheels and axles and avoid the in- 

 creased resistance which is observed 

 when a fresh supply of oil or other sub- 

 stance is applied in quantity beyond that 

 required merely to render the surfaces 

 smooth, and which is supposed to arise 

 from its acting as a wedge at the very 

 acute angle between the wheel and axle 

 when the latter is made in the form of a 

 regular concentric circle. — same. 



Process to form Egyptian Jizure. — 

 Sir Humphrey Davy has discovered that 

 this beautiful pigment which has preserved 

 its brilliancy of tint for more than seven- 

 teen hundred years, may be easily and 

 cheaply made, — fifteen parts of the carbo- 

 nate of soda, with twenty of powdered 

 opaque flints, and three of copper filings, 

 when strongly heated togather for two 

 hours will produce a substance, which, 

 when powdered, will be of a fine deep 

 sky blue, and closely resemble the Egyp- 

 tian Azure in tint. — sam.e. 



A cheap mode of viannfacturing a 

 barometer. — Take a common phial bottle 

 and cut off the rim and part of the neck. 

 This may be done by a piece of a string, 

 or rather whip cord, twisted round it and 

 pulled strongly by two persons in a sawing 

 position, one of them holds ihe bottle 

 firmly in one hand; heated in a few min- 

 utes by the friction of the string, and then 

 dipped suddenly in cold water, the bottle 



will be decapitated more easily than by 

 any other means. 



Let the phial now be filled with clear 

 water and applying the finger to its mouth 

 turn it quickly upside down, on removing 

 the finger it will be found that only a few 

 drops escape. Without cork orstopperof 

 any kind, the water will be retained within 

 the bottle by the pressure of the external 

 air, the weight of air without the phial 

 being so much greater than the small quan- 

 tit}^ within it. Now let a bit of tape 

 be tied round the middle of the bottle, to 

 which the two ends of the string may be 

 attached so as to form a loop to hang on a 

 nail: let it be thu^ suspended in a vertical 

 position, with the mouth open, down- 

 wards, and this is the Barometer. 



When the weather is fair, and inclined 

 to be so the water will be level with the 

 section of the neck or rather elevated above 

 it, and forming a concave surface. When 

 disposed to be wet a drop will appear at 

 the mouth, which will enlarge till it falls, 

 and then another drop, while the humidi- 

 ty of the atmosphere continues. 



If the bottle be held before the fire the 

 water will also drop from it. When the 

 rim is on the bottle the water will not re- 

 main in it. 



It is supposed that the reason of the 

 water dropping when placed near the fire 

 is the rarification of the air making the at- 

 mospheric pressure to be less on the water; 

 antl perhaps the expansion of the water and 

 air* in the phial and in case of the rim 

 being left on, the attraction between the 

 water and the edge of the glass is sufficient 

 to counteract the pressure of the atmos- 

 phere on the water in the phial, which be- 

 ing by that means out of the neck, has no 

 longer any thing to prevent its dropping. — 

 same. 



Black produced by the mixture of 

 colourless liquids. — One of the most in- 

 teresting phenomena in the operation of 

 chemistry, occurs in the decomposition of 

 the sulphate of iron by the gallic acid. — 

 Into a wine glass, containing the infusion 

 of galls, pour a solution of the sulphate of 

 Iron. The gallic acid, from, its superior 

 elective affinity to the iron, detaches it 



*Tliis air is carbonic acid gas ; and vhen water is 

 deprived of it by boiling or by being placed under tin- 

 exhausted receiver of an air pump it loses its briskness, 

 and is rendered flat and unpalatable. 



