690 



Varieties. 



[Dec. 



and wrote for five or six minutes ; he then 

 rose up, with two canons in three parts, one 

 gay and the otlier doleful ; these were tried 

 over separately ; but the surprise of the 

 company was at its height when it was dis- 

 covered that they would go together, and 

 that they produced the most comic effect. 

 In the city of Bologna, Mozart was unani- 

 mously elected member of the Philharmonic 

 Academy ; but not before he had passed 

 through the usual examination. On Octo- 

 ber 9, at 4, p M., he was obliged to attend 

 in the liall of the academy, where he received 

 from the Princeps Academic, and the two 

 censors, in the presence of the whole society, 

 an antiphone to set in four parts. The 

 beadle led him into an anti-chamber, and 

 locked the door. In little more tlian half 

 an hour he was ready, and was there visited 

 by the censors and others, who voted by 

 black or white balls. As the balls v/ere aU 

 white, when Mozart was called in, he was 

 welcomed by a general clapping of hands 

 and the congratulations of the assembled 

 musicians. lie had finished the task in 

 about one-sixth of the time which it com- 

 monly occupied. Had not the abstraction 

 of the miserere, from the Pope's Chapel 

 exhausted admiration, it must have been 

 excited in the highest degree by this per- 

 formance. 



Pectic Acid and the Juice of Carrots — 

 ]M. Vauquelin has analyzed the juice of 

 carrots. The fiillowing is the result of his 

 examination. The juice of carrots contains 

 albumen mixed with a resinous, fatty mat- 

 ter, and manniate. A saccharins principle, 

 which crystallizes with difficulty ; anorganic 

 matter held in solution by the agency of the 

 saccharine principle ; malic acid. The sa- 

 line residuum yielded by the decomposition 

 of the juice is formed of lime and potasli 

 combined with phosphoric, muriatic, and 

 carbonic acids ; the latter results from tlie 

 decomposition of the organic substances. 

 The residuum, insoluble in cold water, con- 

 tains vegetable fibre, pectic acid, or the prin- 

 ciples which yield it, supposing it to exist 

 ready formed. The saline residuum yielded 

 by combustion consists of phosphate and 

 carbonate of lime. The saccharine matter 

 deprived of the insoluble principle dissolved 

 by its agency, is suseeptib.o of the vinous 

 fermentation, but loses this property by the 

 influence of this principle, and is converted 

 into mannite. Pectic acid, when heated 

 in a crucible with excess of potash, furnishes 

 oxalic acid. Common water may be em- 

 ployed for washing the marc of the carrots. 

 If the carbonated are substituted for tlie 

 caustic alkalis the acid is obtained in greater 

 plenty and purity. 



Extreme Tentdty The thinnest sub- 

 stance ever observed is the aqueous film of 



the soap bubble previous to its bursting; 

 yet it is capable of reflecting a faint image 

 of a candle or of the sun. Hence its thick- 

 ness must correspond with what Sir Isaac 

 Newton calls the beginninp of black, which 

 appears in water at a thickness of the 

 l-750,000th part of an inch. 



Improved Paddle-Wheels Among the 



great variety of improved plans for propel- 

 ling vessels which have recently become the 

 subjects of patents, a contrivance proposed 

 by Blr. Perkins, the engineer, and recorded 

 in Mr. Newton's Journal of Arts, is remark- 

 able for its simplicity. The disadvantages 

 attendant upon the ordinary propelling 

 wlieels, from tlie circumstance of the broad 

 face of their paddles pressing on the surface 

 of the water, in entering and lifting the 

 water, in rising out of it, are obviated by 

 passing tl'.e paddles into the water sideways, 

 giving tlie propelling stroke direct, and 

 passing out of the water sideways also. 

 The invention consists, first, in the peculiar 

 position in which the paddle surfaces of the 

 propelling wheels are placed, viz., in radial 

 directions round the periphery of the wheel, 

 and parallel to each other, but Crossing the 

 radial planes of the axis in angles of about 

 45 degrees. Secondly, in placing the shaft 

 or axle of the paddle-wheel at an angle of 

 about 45 degrees from the direction of the 

 keel or the side of the vessel. The object 

 of so arranging the angles of the paddles, 

 and the paddle-wheel sliaft, as respects their 

 rotative positions to each other, and to the 

 keel of the vessel to whicli they are to be 

 applied, is for the purpose of introducing 

 the paddle into the water edgewise, and 

 after giving a direct propelling stroke witli 

 the surface of the paddle at right angles to 

 the keel, to pass it out of the water in asimilar 

 way. By placing the paddles in the obhque 

 positions described, it will be perceived that 

 the two paddles which stand at opposite 

 points of the periphery of tlie wheel will 

 have their faces situated at right angles to 

 each other, the upper paddle always being 

 in a line with the keel, that is, edgewise ; 

 and the lower operating paddle being at 

 right angles to the keel, and a direct stroke 

 of the paddle in the water in the line of the 

 keel, wiU be the result of this arrangement. 

 It certainly cannot be said th.at the paddles 

 of this wheel will give as long a stroke 

 through the water as some other construc- 

 tions of wheels in which the paddles turn 

 upon their axles; but the circumstance of 

 the paddles being firmly fixed, and the parts 

 of the wheel being subject to no other move- 

 ment than that upon its common axle, are 

 advantages which, at sea, wovdd perlia))s 

 recommend the present plan of Mr. Perkins 

 before all others. 



