Show THE AIR WE BREATHE on the evening of thursday november ath 1889 at the regular corion on of the students society of the latter day sainte college a lecture was delivered by dr J E talmage on the subject named above the social hall auditorium was completely filled on the occasion with an attentive and appreciative audience and the remarks of the speaker were followed with unflagging zeal from beginning to end the lecture was one of the public treats for which the faculty of the college in general and dr talmage in particular eular have become noted namely an illustrated discourse one in which every essential point was demonstrated before the eyes of the hearers as well as explained to their ears in treating the air we breathe the lecturer handled his subject in a logical and masterly manner and the apparatus used was of the best we are pleased to present to codr our readers a complete report with sketches of the instruments employed as taken on the spot by our own artist dr talmage said the air we breathe is essential to our existence and probably none other argument as an to the importance of the subject is requisite it is an everyday every day subject indeed and one of endless instruction st one cannot contemplate the properties of the air without a feeling of profound amazement at the strange association of simple means and wondrous results men and animals die if deprived of air for r respiration eb pi ration the oxygen of the atmosphere being necessary to enter into combination with the waste products of their bodies and to remove such from their system the plant j is no less dependent upon the air for its support indeed the vegetable fabric has been regarded by scientific investigators as organized air the explanation is simple the air contains among other constituents is a small oman amount of carbon dioxide gas only a cubic inch of the gas in an vy entire cubic foot of the air yet sufficient for all natural purposes the plant absorbs the carbon dioxide VE and decomposes it fixing the carbon in its own tissues and returning the oxygen in a free and useful state to A the air again but we aim tonight to consider only the physical properties arties of the air we breathe the chemical characteristics must be excluded for the present it is believed that the earth is surrounded with a layer of air of definite extent NO p VAA part af pf fe 0 earths surface is known at which the proofs of this atmosphere are not strong and conclusive while walking upon the ground we are tu iu fact moving upon the bottom of the aerial ocean as crabs might crawl craw on en the alie sea bed owing to its transparency however the atmosphere is not visible to our organs of sight eight and we must adopt other means than trying I 1 to seethe see the wind of testing its presence these means are am the performing of careful experiments which are in reality questions propounded to nature the resulting phenomena are her answers and they are clear I 1 have on the table as you see ON a a glass vessel containing water figu figure re 1 upon the water floats a large flat cork to which a bit of candle has been dand this candle we will ignite here is a bell y j jar open at the bot jl torn tom and closed above 1 I 1 l an inverted tumbler figi would do as well for the operation if conducted on a smaller scale As you observe I 1 lower the bell jar over the floating candle and press downward until the jar j ar is entirely anti rely submerged yet liet as all can seo see the floating candle has not risen into the jar consequently we know the water has not entered the immersed vessel there j is a commonly quoted law that liquids tend to find their level and they will succeed too unless the tendency be opposed by a stronger force in this case there must be something within the bell jar which presses downward upon the surface of the water and prevents its ite rising that something is the atmosphere A further proof may be made thus I 1 have here figure 2 a lt A rig fig a 2 large two necked bottle A each mouth carrying sarr ying a perforated cork A common wide mouthed bottle would do if provided with a cork having two bolef holeb bored through through one cork a funnel tube B passes the end reaching to the bottom of the vessel in the other cork a bent delivery tube 0 is inserted this tube terminates DateS beneath the our bur firce of gwawr jn in a pan and overt heend of the tube a bottle D previously filled with water is inverted As AB I 1 pour water into the large bottle A the lower end of the funnel tube is sealed and the only exit is through the delivery tube C As I 1 pour the water bubbles rise from the end of the tube and displace the water in the inverted vessel D by measurement it can be shown that just as much water is displaced from D as is poured into B in other words as much air is forced out of A as water i poured in the invisible atmosphere then possesses this property among others that it occupies a definite amount of space and prevents other matter occupying the same space at the same time it is itself therefore a species of matter its properties are definite here figure 8 is an ordinary wide necked bottle this I 1 fill with water and press a piece of 3 paper mouth then while holding the paper in close can tact I 1 invert the bottle and now lol lo I 1 remove my hand feigt fig a from the paper yet the latter still remains over the mouth and not a drop of water escapes evidently there must be some support by which the paper is kept over the bottle mouth else the weight of the contained water would force the cover away and would itself escape we can only ascribe this effect to the upward pressure of the atmosphere against the under side of the paper pape r th the e atin atmospheric 08 pharic pressure must at least be greater than the downward pressure of the water in the bottle but let us vary the experiment I 1 take a bottle figure 4 similar to A the one last used but te over the mouth of this one a piece of coarse netting has been tied I 1 fill the vessel with water by pouring through the netting place paper over the mouth and invert the FU 4 bottle as before now for the variation I 1 care carefully fully slide the paper away from the mouth and still AIR the water does not run out it is frequently said that water cannot be carried in a sieve but we keep it confined b here ere with a floor of netting for it to rest upon in this case the surface tension of the liquid forms a film from mesh to mesh of the netting and the upward pres oum of the acts act upon at 9 this layer aej an sustains the water within the vessel here I 1 take a glass tube about three feet long closed at one end this I 1 fill with water and then invert with the open end below the surface of water in this large vessel the water does not run out of the tube how is it sustained then ea evidently by the downward pressure of the air on the surface of the liquid in the outer vessel this pressure is transmitted to the contents of the tube if the water should run out of the tube while the open end of f the bottle ia kept below the water surface in the other vessel no air could enter and there would be a vacuum in the tube that is to say a space which is devoid even of air many centuries ago people observed this phenomenon and ex r it by saying nature hates a vacuum now a question of in terest is this how strong is nature hatred toward a vacuum Is the pressure odthe of the air of measurable or i of infinite strength this query has been answered by an expert y ment which we cannot well repeat here on this occasion A tube J thirty six feet long was filled with water and inverted in water and fell to a height of thirty four feet leaving an empty space a vacuum in fact in the top of the tube to account for this phenomenon the saying arose nature does not hate a vacuum beyond thirty four feet instead of experimenting with so long a tube we will take here figure 6 5 a tube 36 inches long fill 1111 it with mercury and jit then invert it in a ves v sel of the same liquid r the mercury or quicksilver falls inthe tube to a height of nearly 26 inches at this altitude but at the sea lev level elthe the column would have been 30 inches high a vacuum being ria found in the upper appe r part of the tube now quicksilver or mercury is 13 times heavier than water and the height at which the water stands in the inverted tube viz 34 84 feet to is just as times higher than th anthe the mercury column which reaches 30 80 inches only the pressure of the air at the sea am level therefore Is just sufficient to th sustain a column of mercury 30 80 inches high and one of water 84 feet high if the mercury tube had bad a cross section of one square inch and the mercury within stood 00 00 i inches high there would be within the tube 30 cubic inches of mercury and this would weigh about 15 pounds hence we usually consider the atmospheric pressure at sea level to be about 15 pounds per square inch at this rate the air pressure in the palm of the hand say five inches long and three inches broad would be about pounds the pressure on the lid of a box 40 inches square would be pounds and the pressure on the body of a man of ordinary size would be about 15 tons we are usually unconscious of this great power owing to the fact that the pressure manifests itself equally on all sides of objects on the back of the hand as well as the palm and even within the interstices of the flesh on the lower side of the box lid as well as above and on all sides including the inside of the human body Ite reference ference has been made several times already to the fact that the mercury column in the experiment last performed is higher at the sea level than at a greater altitude this is so because the air becomes rarer as we ascend above the earths surface and the pressure that it ex arte is correspondingly less such an instrument a tube of proper length filled with mercury and inverted in mercury constitutes the barometer a device designed to indicate the degree of atmospheric pressure under any particular circumstances by carefully noting the readings of a barometer it will be found that even at the same station the air pressure is variable by considering such variation vax lation some prognostication of the weather may be made though no definite rules have been adduced many people claim for the barometer more than the instrument deserves and say that it is a sure indicator of the weather changes whereas in reality the instrument simply reveals the fact of the change in atmospheric density and these changes we interpret not always rightly in consulting the barometer with a view of determining the weather forecasts attention must be paid to the place at which the observation is made thus in london should the barometer register as low as 29 inches heavy storma would be expected while in utah the barometer column seldom rises above 26 inches while speaking of barometers passing attention might be called to an ad instrument of common sale known as the storm glass it consists of a short sealed tube of glass glan containing a 4 chemical solution of a y 7 y solid the accompanying 4 instructions are to watch the solutions and as the appearance of the crystals change so so will the weather vary remembering the tube is of aigid glass and hermetically sealed the fact is at once clear that no variation in atmospheric pressure can possibly affect the con contents of the tube the instrument is a pretty ornament and a good selling article but its farther use as a barometer would be hard to find find there are many common instruments dependent upon air pressure we have here a glass tube figure 6 in which a bulb has been blown by inserting the lower end in liquid and applying suction above the tube may be wholly or partially filled and the contents may be easily kept within or allowed to drop or to flow by applying PI y ing the finger at the top and controlling the ingress of air such an fig 6 instrument is called a pipette and is of great value in transferring small quantities of liquid from one vessel to another the dyphon figure 7 is another simple but efficient device it con fig 7 slots of a bent tube one arm of which is longer than the other by inserting the short arm in a liquid and then applying suction at the other end till til the tube is filled the flow may be started and this will continue till the liquid has sunk below the entrance to the tube siphons of modified form may be made so as to produce fountain sprays and the like upon this principle intermittent springs are believed to operate the water gat gathering herhag in a cave within theearta the earth until it finds an outlet through a dyphon shaped soaped channel and then continuing to flow till it has sunk below the entrance to the outlet con conduit dult but far more impressive results in air pressure experiments may be made by the aad of the sk pura adhere figure 8 is a very efficient instrument of this kind X 11 l 1 U fig 8 tills this form is known as a lever air pump its structure can best be understood from an examination of its ite parts see figure 9 is the barrel P ing fig 9 or cylinder in which works a tight 4 viston piston which is operated by means of a rod and lever A valve in the cylinder cyl linder is made to open only in an upward direction and a second valve in the piston opens in the samme anoe direction on the plate from which a pipe passes to the cylinder a receiver is placed and as the lever is operated successive atiee aes of air are withdrawn from the receiver so that a vacuum will be produced zet us test the power of this in ent here is a small cylinder f of glass open at both ends except that over one a piece of bladder bee baa been tightly tied As you see I 1 I 1 place the uncovered end on the plate of the air pump and then the gentleman who is assisting me exhausts the air from the cylinder the pressure of the external air being now unbalanced by any pres ure sure from within presses on the bladder covering forces it inward 1 until ah there you heard it burst with a report like that of a gun now we will tie a piece of sheet rubber over the cylinder in place of the bladder and exhaust once more As you observe the rubber is forced inward till it completely lines the 1 inside of the cylinder alet us tw vary the operation once fagain instead of the bladder or the rubber I 1 will ask this gentle nian to lend we me his hand he conent depts I 1 adjust his bis hand figure 1 ta over avar the glass and now we A will exhaust the air from within I 1 see the tl emens hand drawn forcibly into the cylinder and at every stroke I 1 notice a faint cloud of perspiration al ration filling t the h e cylinder fig 10 the gentleman is unable to lift his hand band from the glass till we admit the air but an illustration even mo more re striking still is this I 1 take now a paid of iron half globes made to fit together at their edges and provided with convenient handles bandies figure 11 you observe fig 11 however that it is a very simple process to separate them now I 1 attach the hemispheres to the pump and the air to is withdrawn I 1 will request some of the gentlemen to pull them apart here a number of men tried to separate the heals hemispheres and caused considerable merriment by their lusty and hearty efforts though the globe was only five inches in diameter it required eight men to separate its parts the doctor resumed these pieces of apparatus are called the magdeburg hemispheres in remembrance mem brance of the little saxon town at which the trial was first made here is another device of interest figure 12 it is called the weight lifter and consists as you see of a cylinder 0 in which operates operate a R piston P to which a weight of thirty pounds is attached A tube leads from the top of the cylinder to the pump and now observe as the air is exhausted fig 12 from within the cylinder the pressure on the lower surface of the piston forces it upward raising the heavy |