Complete Text (Part 8)

of glass and cause the sheet of glass to roll without slip- ping on the model, always touching it in two points at least. The grease will be partly transferred from the glass to the model at the points of contact, and there will be traces on the model of the node-couple curves, and on the glass of the corresponding plane curves. If we now copy on paper the curve traced out on the glass and cut it out, we may bend the paper so that the cut edges shall coincide with the two node-couple «. ICE .. AND .. REFRIGERATION .°. 23 curves, and the paper between these curves will form the derived surface representing the state of the body when part is in one physical state and part in another. There is one position of the tangent plane in which it touches the primitive surface in three points. - points represent the solid, liquid, and gaseous states of the substance when the temperature and the pressure are such that the three states can exist tovether in equi- librium. The plane triangle, of which these points are the angles, represents all possible mixtures of these three stat state, I. grammes in the liquid state, and V grammes in the state of vapor, this condition of the substance will be represented by a point in the triangle which is the center of gravity of masses S, L and V placed at the corresponding angular points, From this position of the tangent plane it may roll on the primitive surface in three directions so as in cach case to touch it at two points. We thus obtain three sheets of the derived surface, the first connecting the solid and liquid states, the second the liquid and yas- eous states, and the third the gaseous and solid states. These three developable surfaces, together with the plane triangle S L V, constitute what Professor Gibbs calls the Surface of Dissipated Energy. Of the three developable surfaces the first and third, those which connect the solid state with the liquid and gaseous, have been experimentally investigated only to a short distance from the triangle S L V; but the sheet which connects the liquid and gaseous states has heen thoroughly explored. The experiments of Cagniard de la Tour and the numerical determinations of Andrews show that the hese For instance, if there are S grammes in the solid curves traced out by the two points of contact of the doubly tangent plane unite in a point which represents what Andrews calls the critical state. At this point the two points of contact of the rolling tangent plane coal- esce, and if the plane continues to roll on the surface it will touch it at one point only. If the primitive surface forms a continuous sheet beneath the surface of dissipated energy, it cannot be at all points convexo-convex up- A eC ward. For let A D be the line joining two corresponding points of contact of the doubly tangent plane, and let A B CD be the section of the primitive surface by a verti- cal plane through A D, then it is manifest that the curve A BC PD must in some part of its course be concave up- ward. Now a point on the primitive surface at which either of its principal curvatures is concave upward repre- sents a state of the body which is essentially unstable. Part of the primitive surface, therefore, if it is continu- ous, must represent states of the body essentially un- stable. If, therefore, the primitive surface is continu- ous, there must be a region representing states essen- tially unstable, because one or both of the principal curvatures is concave upward. This region is bounded by what is called in geometry the sfimode curve. Beyond this curve the surface is convexo-convex, but the tangent plane still cuts the surface at some more or less distant point till we come to the curve of the node-couple, at which the tangent plane touches the surface at two points. Beyond this the tangent plane lies entirely D 24 «. ICE .. AND ., REFRIGERATION .:. JULY, 1893. above the surface, and the corresponding state of the body is essentially stable. The region between the spinode curve and the node- couple curve represents states of the body which, though stable when the whole substance is homogeneous, are liable to sudden change if a portion of the same sub- stance in another state is present. Since every vertical section through two correspond- ing points of contact must cut the spinode curve at the points of inflexion B and C, the chord A D of the node- couple curve and the chord B C of the spinode curve must coincide at the critical point, so that at this point the spinode curve and the two branches of the node- couple curve coalesce and have a common tangent. This point is called in geometry the /acnoda/ point. ‘Thermodynamic Surface, uv O Origin. OV Axis of volume. O ¢ Axis of entropy. Oe Axis of energy. P,... P, Isopiestics or lines of equal pressure. Of these P, represents a negative pressure, or, in other words, a tension, such as may exist in solids and in some liquids. T,...T, Isothermals, or lines of equal tempera- ture. The curves T, and T, have branches in the form of closed loops. FGHC. Tothe right of this line the substance is gaseous and absolutely stable. To the left of F G it may condense into the solid state, and to the left of G H C it may condense into the liquid state. CKLMN. Below this line the substance is liquid and absolutely stable. To the right of L KC it may evaporate, to the left of L MN it may solidify. QRSE. To the left of this line the substance is solid and absolutely stable. To the right of S RQ it may melt, and above S E may evaporate. C is the critical point of the liquid and gaseous states. Below this point there is no discontinuity of states. C is called in geometry the tacnodal point. The curves FG, GH CKL, LMN, QR SandSE are branches of what is called in geometry the node- couple curve. The curves X C X and Y Y are branches of the spinode curve. Above this curve the substance is absolutely un- stable. Between it and the node-couple curve the sub- stance is stable, but only if homogeneous. The plane triangle S L G represents that state of uniform pressure and temperature at which the sub- stance can be partly solid, partly liquid and partly gaseous. The straight lines represent states of uniform press- ure and temperature in which two different states are in equilibrium. SG and E F between solid and gaseous. G Land K H between liquid and gaseous. SL, R M and QN between solid and liquid. The surface of dissipated energy consists of the plane triangle S L G and the three developable surfaces of which the generating lines are those above mentioned. This surface liesabove the primitive thermodynamic surface, and touches it along the node-couple curve. IMPURE ICE QUESTION. F all places in the world, New Orleans would seem © to be the last where the ‘impure ice” craze could find lodgment; but about a month ago it broke out there with all the fury of an epidemic, and the theory that ««chemicals were used in the water by some manu- facturers to reduce the cost” was gravely discussed by the learned reportorial staff of certain daily papers! A filter slightly out of order was no doubt at the bottom of the trouble, while now and then a little rust may have appeared in the ‘‘core.” The excitement has subsided, and the ‘‘daily bulletins " have been discontinued. A REPORTER at Rochester, N. Y., found a mare's nest there recently, and in the absence of other sensation for the day worked up a “very good thing,” which reminds the average newspaper man of Mark Twain's early reportorial experiences in Virginia City writing up the «shay market” (of one lone load). The board of health, however, seemed to preserve their equilibrium under the pressure, and allayed any nervousness by assuring the florid and imaginative scribe that when they found any impure ice, the ordinance would enable them to deal with it. Tue city council’s committee at Boston reported, May 26, that no action was necessary on the order in regard to an examination of ice and the source of supply of the same, by the inspector of milk and vinegar, as the state board of health has recently made two exhaus- tive examinations of the ice sources and supply. And the crank, like the villain in the play, is ‘‘crushed again.” ICE & REFRIGERATION (ILLUSTRATED ) A Monthly Review of the Ice, Ice Making, Refrigerating, Cold Storage and Kindred Trades. OFFICIAL ORGAN oF THE SOUTHERN Ice EXCHANGE, THE SOUTH-WEST Ick MANUFACTURERS ASSOCIATION, THE TEXAS ICE MANUFACTURERS ASSOCIATION AND THE FLORIDA ICR MANUFACTURERS ASSOCIATION. RATES OF SUBSCRIPTION. IN ADVANCE, POSTAGE PREPAID. United States, Canada and Mexico, All other Countries, - Single copies 25 cents. Remittances must be made b; tioney orders, checks or drafts on New York, Chicago or London, Ce 300 Advertising rates on application to the offices, post-office orders, postal notes, international able FOWLER J.-F. NICKERSON JNO. GLENN COLLINS, H. S. RICH & CO. PUBLISHERS, 171 La Salle St., Cor. Monroe, CHICAGO. Entered at the Chicago Post-office as second class mail matter. to act of Congress, in the year 1893, by H. S. RICH & CO.,in ice of the Librarian of Congress, at Washington, D. C. Alt Rights Reserved. Entered accord 206 Broadway, Cor. Fulton, NEW YORK. INDEX TO ADVERTISERS. droth & Root Mfg. Co. Boa Foundry & Machine co bunbbzasu.s Armatrong-Gilbert Cork Co. Armstrong Mig. Co.. Arnold & C g Baeder, Adamson & C: Barrath, Edw., & Co. Bartlett, Hayward & Co, Outsic Back Cover. Battle Creek Machinery Co. yee zeal Fein Briggs, John N. Bufiato Retrig. Machine Co. Burnham, Praaklin P Burns Mfy. Co... Callahan, WP. & C Canfield, H. 0. Eaton Erect Cover. Cardell, James D., & Co: Case Refrig: Macitine Co. Gastie ice Machinery Co... Chapman Valve Mfr Co. Chate Refrigerating Co. : Ghicagg Automatic Reyisice Co.-- appr B. Py Ammonia CO....... GletGiana Electrical Mw. és Columbus Iron Works C Gonros.'B. J. & Co. ook, A.D Gorter B, rw E Graft Refrigerating Mach randall Packing Co. vai Crosby Steam Gage & Valve Co.... 2 Cyclops Machine Works . a G5linder Scale Co..... Dean Bros. Steam Pump Works.. Deane Steam Pump C De Laval Separator Co.. De La Vergne Refrig. Mach € De Long & French. .. Deming Co,, The...... Dexter, A. I Directory of ice Factories, Ice Dealers & Cold Storage Houses. . Dizon, Lon, Crucible Co, Dodge. Eiictprise Boiler Core Epping, Carpenter & C Farrell & Rem Fay Armstrong C: Corie Go Featherstoue's Sons, John. Fletcher, I. D. Foster Pump Works... Frick Co. Frontier Iron Works. Garlock Packing Co. Gifford Bros........ Goodrich, B. F., Co @) Goss, J.C. & C Globe Mineral Wooi Co’: Gum Elastic Roofing Co. Hamilton Construction & Tool Co.40 Ma- Harrisburg Foundry and chine Co... Harrisburg Pipe B vi Harrison Safety Boilec Work Henderson, Thoens & Gerdes.....00 Hendrick Mfg. Co.. Ltd, Hercules Iron Works. Hill Machine Co,, Tne. Hillyer, E.C. & Co... Hilpert’ & Chander Holmes, S.T.... Ice and Cold Machine Co.... .....69 Johnson, John Keasbey, Robert A. Keasbe: & aatiaod Co., The. Kellogg, E. H. & C Kemper, Ai Kenly, D. F. & Kiechler Mfg. &. Kilbourn, J. K. Koenig & Luhrs Carriage Co. Koenigsberg, Jos. Lackawanna Lubricating Cc Laidlaw-Dunn-tordon Co., The: Lawson, Enoch... . Louisville Pipe Ben Love & Co.. McNeil, J. C., Co. Macan & Co....... Maris & Beekley . Maritzen, Aug.. Mason Regulator Co Mayer, C. s Merchant & Co Merrill & Webrle Charcoal Coll 143 Miami Valley Boiler Z Mitchell, Thos... Morse El Motley, TI Murray Iron Work Nason Ice Machine C National Am. Co., Cover. National Pipe Rending Co. x N- ¥. Coal Tar Chemical Cov... 045 Nicholson, J.T. & So an ightingale, S.C ‘& Childs ian fron Enamel Co .. “ 265 Outside Back Osborne Steam Engineering Co...38 Peirce, A. H. Mfg. Co. seed Penberthy Injector Co.. Pennsylvania Iron Worka Co. Philper, Phoenix Machine Works., cd Phosphor Bronze Sm’lt’g Co., Ltd.49 Polar Construction Co. 50 Pontifex Ice Machine Co., The. Post, Edward C.. Pusey, Lea. Queen City Omnibus and Wagon Mfg. Co.. 48 Reading Iron Co... Remington Machine C Ripley Isinglass .. Russell & Co... Wie, Irvin er Manufacturing Co, Vulcan Iron Works, The. Wainwright Mfg.Co.,of Mast Wants, and For Sale, Etc. Samson Steam Forge Co... Boe4 BEBB basses Bru ton H. Fd Co.-. entre 8 & Campbeli” “ West eral Wool Co. Westinghouse, Church, Kerr & 17 pe Co. 34 Wolt Otto Go. tas ide Frout Cover 5 Wolt, The Fred WC 1B Surombore, Alien & Ce aa to v4 Truslow & Co... wy Welent 2B. & Co a U.S. Mineral Wool Co .. +50 York Mfg. Co., Inside of Back Cover A MUDDLED PHILOSOPHER. HE American Dairyman, of New York city, T recent issue, devotes some five columns of space to an attack on manufactured ice, which, as a specimen of ‘special pleading,” is about as near the climax of “‘biggod nonsense,” as Mr. Sparkler used to say, as it is possible for the average mind out of an asylum to attainto. The befuddled gentleman, in the first instance, insists that ice as gathered from a running stream, “ like our beautiful Hudson,” is ‘‘shown in its most perfect state ”—‘‘in its purest condition.” In which view he takes direct issue with all sanitarians, who insist that ice is not always thus ‘‘ shown inits purest condition,” from the fact that the Hudson is, in certain portions, at least, contaminated with sewage. The reasoning of the be- fuddled philosopher as to natural ice is carried out on the same line indefinitely; and he has the assurance even to quote Ice AND REFRIGERATION to substantiate his claim that natural ice is pure always and under all circum- stances—a quotation made in the true Dogberry style, in that he ignoresall the incidental remarks made about the contamination of rivers by sewage. Water that is pure enough to drink is, of course, pure enough to use as ice; but, on the contrary, water that is unfit to use as water is unfit to use as ice—a view, or fact, that our muddled special pleader is at some pains to suppress. But it is when he undertakes to prove that manufact- ured ice, as now made for the trade, is always and nec- essarily impure, that the gentleman really turns himself loose. He says: Repulsive odors seem inseparable from its melting state. The unmistakable stench of the refrigerator where it is kept is an ever present invitation to disease. If there were no other objection to it, this should be an all-sufficient one for an avoid- ance of itsuse. In melting it releases the chemicals that caused its solidity, and these are actively detrimental to health. With the use of natural ice a more pleasing story is casily told. In its formation nature's chemistry employs elements that are essential to organic life, and these, when reduced to their elementary state, are harmless. From all of which it must appear to every intelligent reader that the gentleman is talking very vigorously ««through his hat.” He clearly has no idea of how ice is made. To talk of odors from the melting ice is an absurdity. Undoubtedly a refrigerator that is not sys- tematically cleaned will stink, but the question arises, Is it the melting ice or the contents of the food receptacle that causes the odors? In gg out of 100 cases it is un- doubtedly the latter, as every good housewife knows. As to the idea that the melting of ice ‘‘releases the chemica] that caused its solidity,” that of course is too ridiculous for serious consideration. The special pleas against manufactured ice, however, rest on three points: (1) Water is taken by one New York in a 26 «. ICE .. AND .*. REFRIGERATION .°. JULY, 1993. factory from the river between two sewers. [This un- doubtedly is a reference to ‘“ cooling water,” if the fact be true. But it is strange that he does not recollect that some of the natural ice, that is, ‘‘ ice in its purest condition,” may be frozen sewage.] (2) That pure dis- tilled water is too expensive for ice making; and (3) that the air of the factory contaminates this water even after distillation; and he quotes in the same ex-parfe manner Dr. Prudden when the latter says: It is extremely difficult to prepare germ-free water on a large scale, and almost impossible to keep it so if once prepared, because every exposure to the air or contact with utensils in common use brings to it—and often large numbers of—germs which can live and grow in water. . The ‘‘cussedness” of the gentleman’s system of quotation of authorities is amply illustrated right here; for he has systematically and ‘with malice afore- thought,” suppressed the vital point, that is, the con- cluding sentence of the paragraph quoted, to wit: “But these small numbers of common bacteria are not of the slightest importance to the salubrity of the water.” Prudden in fact says: So far as the salubrity of the natural ice is concerned, we may rest assured that as regards bacteria, one is just as whole- some as the other, provided the water is pure. If the water is impure from sewage or other unwholesome thing, then the natural ice is never fit for domestic use. If water is impure, the processes of artificial ice making, if carefully performed, are capable of furnishing, even from it, a product which is harmless and wholesome,