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OUR

ARM-CHAIR.HEALTH DEPARTMENT.

OUR ARM- CHAIR. THE BEST ORGANS AT LOWEST PRICES.-The Mason & Hamlin Organ Company, which has the largest factory for this class of instruments in the world, and enjoys the reputation of making the best instruments, having taken the Medal at the Paris Exposition, and any number at the principal fairs in this country, announce an important reduction of prices on several styles of organs. They now furnish a Four Octave Organ for Fifty Dollars, and a Double Reed Five Octave Organ, with five stops, in carved and paneled case, for One Hundred and Twenty-Five Dollars. This Company have also recently introduced a new invention in several styles of their Organs. It is termed the Mason & Hamlin Improved Vox Humana, and excites much interest among lovers of music, very much enlarging the variety and scope ofthe instrument. At their warerooms, 596 Broadway, New York, may usually be found several hundred of Organs, in all imaginable styles, and great variety in prices. This gives an idea of the extent of the business. They send Orgaus to almost every civilized Nation on the globe, and not a few to Nations regarded as uncivilized. A CHALLENGE FROM A LADY.-Wheeler & Wilson have received the following letter, which speaks for itself: New York, October 20, 1868. MESSRS. WHEELER & WILSON, 625 Broadway-Gentlemen : Referring to the challenge of Mr. Pratt, whose Wheeler & Wilson sewing-machine has been in use ten years without repairing, I beg leave to state that I have used my Wheeler & Wilson sewing-machine, in family sewing, fourteen years without even the most trifling repairs, and it is now in so good condition that I would not exchange it for your latest number (now upward of 350,000.) One needle served me more than a year for fine sewing. Can any one beat this ? Yours truly, MRS. ANNE WARNER. Any one who can give a better report than this will be entitled to one of our new tucking gauges. WHEELER & WILSON MANUFACTURING CO. SPLENDID ENGRAVINGS.- Either of the following engravings will be sent, post-paid, for the annexed prices : Star of Bethlehem, $2.00 Bunyan In Jail, 2.00 2.00 Bunyan On Trial, Washington and His Generals. 2.00 Or the whole four, to one address, for $5.00 . Or any two for $3.00. Address, PETERSON'S MAGAZINE, 306 Chestnut street, Philadelphia.

THE BEST CATALOGUE of cheap, yet good books for reading, is that of T. B. Peterson & Brothers. If you wish to buy an entertaining novel, especially, send for their catalogue, in which you will find the titles of some five hundred excellent fictions, by popular authors. Their address is T. B. Peterson & Brothers, No. 306 Chestnut street, Philadelphia, Pa. HOLIDAY JOURNAL.- NEW No.- FREE.-For the Holidays of 1868-9, containing a Christmas Story, Parlor Plays, Magic Sports, Odd Tricks, Queer Experiments, Problems, Puzzles, etc. 16 large pages, illustrated, Sent Free. Address, ADAMS & Co., Publishers, 25 Broomfield street, Boston, Mass. wwwwa wwwwww HEALTH DEPARTMENT. TO PURIFY THE AIR OF AN APARTMENT.-The best method of effecting this will be obvious, if we consider the infinence heat exercises on the atmosphere . Air is expanded and rendered specifically lighter at the ordinary temperature on the application of heat. Hence in every room heated above the temperature of the atmosphere, there is a continual cur-

rent of air in circulation. Hot air in chimneys ascends, and creates a draught toward the fire-place, whilst the hot air in churches, theatres, and other buildings, passes through the gratings in their ceilings, and its place is supplied bythe flow of cold, fresh air through the windows and door-ways in the lower parts of these buildings. The following simple experiment can be easily performed, and is highly instructive: Take a lamp, or candle, and hold it to the top of the door-way of a crowded apartment, or of a room in which there is a fire; the hot air will be found escaping out of the room at the top of the door-way, as will be indicated by the outward direction of the flame. If the lamp be placed on the floor, the cold air will be found to be coming in at the bottom of the door-way. If, now, the lamp be gradually raised from the bottom to the top, the flame at first inflected inwardly, will be seen gradually to become vertical as the lamp approaches the middle of the door-way, and finally it will be again blown outwardly when the lamp reaches its Gummit. It would appear from this, that in the middle of the door-way the temperature of the air is uniform, hence there is no current either in or out of the apartment. The whole experiment is highly interesting and instructive, and proves that a fire is an excellent ventilator. Hence, to ventilate an apartment thoroughly, it is only necessary to kindle a good fire, and let the air have free access through the doorway and windows ; the fire will create a current of fresh air into the apartment, and its atmosphere will be thus kept continually changed. We would remark, in conclusion, that those moving masses of air called winds, are produced in a similar way. The sun is the great cause of winds ; its heat is unequally diffused over the carth's surface, and the air becomes consequently heated in one part to a greater degree than in another. The hot air rises, and its place is supplied by the flow of the colder air from the surrounding parts. When the vacuum thus created is sudden, and the flow of the surrounding air is violent, the meeting of winds from all points ofthe compass produces at sea the phenomena of water-spouts, and on land whirlwinds, caused by the air ascending in a spiral form into the higher regions of the atmosphere. There are a number of causes which produce inequalities of temperature in the atmosphere ; some of the most obvious of which are the alternation of night and day, and the occurrence of cloudy and unclouded skies. The air must be necessarily heated when illumined by the rays of the sun, and cooled when those rays are withdrawn.

HOLIDAY AMUSEMENTS . INSTANTANEOUS FREEZING .-During frosty weather, let a vessel be half filled with water, cover it closely, and place it in the open air, in a situation where it will not experience any commotion ; it will thereby frequently acquire a degree of cold more intense than that of ice, without being frozen. If the vessel, however, be agitated ever so little, or receive even a slight blow, the water will immediately freeze with singular rapidity. The cause of this phenomenon is, that water does not congeal unless its particles uuite together, and assume among themselves a new arrangement. The colder the water becomes , the nearer its particles approach each other; and the fluid which keeps it in fusion gradually escapes; but the shaking of the vessel destroys the equilibrium, and the particles fall one upon another, uniting in a mass ofice. CHARCOAL IN SUGAR.- The elements of sugar are carbon and water, as may be proved by the following experiment: Put into a glass a tablespoonful of powdered sugar, and mix it into a thin paste with a little water, and rather more than its bulk of sulphuric acid ; stir the mixture together, the sugar will soon blacken, froth up, and shoot like a caufiflower out of the glass; and during the separation of the charcoal, a large quantity of steam will also be evolved.