'4 AMERICAN SOCIETY OF MECHANICAL ENGINEERS. Non-Conducting Coverings for Steam Pipes. Prof. JOHN M. ORDWAY. Presented before the Society by C. J. H. Woodbury, Boston, Mass, (member of the Society). A Record of Experiments made for the Boston Manu- facturers’ Mutual Fire Insurance Company, Reprinted from Volumes V. and VI. of the Transactions. 12 West 31st St., New York City. KJniv.of 111. Library 52 / S-3/ CXXXV.* EXPERIMENTS UPON NON-CONDUCTING COVERINGS FOR STEAM PIPES. BY PROF. JOHN M. ORDWAY, BOSTON, MASS. PRESENTED BY C. J. H. WOODBURY, BOSTON, MASS. INTRODUCTION. In addition to the usual number of fires caused by steam-heat- ing pipes, there have been several fires during the past year from the coverings of steam pipes. An examination of the matter showed that neither dye-stuffs nor oils were present in these coverings, so that the fires could not be ascribed to spontaneous combustion. There seemed to be very little accurate knowledge respecting the efficiency of steam-pipe coverings, although their general im- portance is universally acknowledged. There was so much at stake in this matter that the under- writers in interest considered that it would be desirable to inves- tigate the question of these non-conductors, both in respect to any possible dangers of combustion and also to the measure of their economic efficiency. The question was submitted to Pro- fessor Ordway, and, by the courtesy of Mr. Edward Atkinson, President of the Boston Manufacturers’ Mutual Fire Insurance Company, I have the opportunity of presenting to you that por- tion of Professor Ordway’ s report, treating of the value of the coverings, with a description of the methods employed, and the results obtained. C. J. H. W. In undertaking an investigation of steam-pipe coverings, it was necessary, in the first place, to decide what method, or methods, should be used for determining their efficiency as non-conductors of heat. I have met with no recorded experiments of which the details are given in full, but it seems that, in general, two modes have been employed heretofore. In one — the air chamber method — a portion of the covered pipe, while in use, is inclosed in a small box so as to form a close chamber into which the bulb of a ther- mometer is inserted. The inverse ratio of the temperatures indi- * Presented at the New York meeting (October, 1883) of the American Society of Mechanical Engineers, and forming part of Volume V. of the Transactions. 74 EXPERIMENTS UPON NON-CONDUCTING cated by the thermometer in different trials is supposed to show the relative excellence of the different coverings. In the second, or condensation method, the steam is allowed to pass from the main pipe out into a side branch covered with the substance in question, and so arranged that whatever water is formed in an observed number of minutes may be drawn off from time to time and weighed or measured. The water is reckoned as having parted with as much latent heat as is contained in that weight of dry steam. The air-chamber method it might be thought easy to carry out, but it is difficult to fit a box of any kind so closely to the covering that there will be no circulation of air into and out of the inclosed space. Of course, a lack of tightness will fatally vitiate the experiment. Again, a box surrounding the pipe and covering, presents a large radiating and cooling surface as com- pared with the covering itself ; and there is no ready way of de- termining the amount of this continual radiation which increases with the temperature of the air within the chamber. There is no perfect non-conductor wherewith we can surround the air chamber, so as to confine therein all the heat received. If we could prevent all outward radiation, the cavity would, sooner or later, acquire the temperature of the steam in the pipe, and all coverings would finally give the same result. The only way to make useful observations would be to start with everything cold, and find the time required to raise the air in the chamber to a given temperature. This is, however, hardly practicable. We cannot obtain' absolute or quantitative results by this method, and the comparative figures require indeterminable cor- rections. Still it was thought advisable to try this plan among others, and see how far the results would correspond to those found by more definitive modes. Accordingly, the apparatus shown in Figs. 18 and 19 was devised and used for this purpose. Fig. 18 shows a transverse section of the whole apparatus as it was mounted, together with the covering and pipe. Fig. 19 repre- sents one-half as seen from the side next the covering. In mak- ing the apparatus, pieces of white pine plank, e, are squared and rabbeted at the ends to receive the wooden braces, //, which are firmly screwed on. A two-incli hole is bored from the inner side, two-thirds through, to form the cylindrical chamber c. The inner side is then planed out so that the concavity s, when properly lined, may exactly fit the convexity of the covering to be tried. COVERINGS FOR STEAM PIPES. 75 A hole, x , is bored from the top edge down into the chamber c. The concavity s and the chamber c are lined with thick woolen blanket, the large piece d being held in place by tacks n n. The halves are clamped on the pipe-covering with the four iron rods g, and tightened to a close lit with the thumb nuts h. Ther- mometers, t t, are let down into the chambers, a little cotton wool being crowded in around the stems at x, to prevent the ingress of cold air. The two chambers so applied serve to check each other; for if the thermometers differ much, there is a defect in the adjustment. A difference of two or three degrees, however, may occur, on ac- count of an inequality in the two sides of the covering itself. The condensation method is indirect, and therefore a little uncer- tain. It necessarily assumes that the pipe is all the time filled with dry steam. But we can hardly expect to have pure steam when its generation is going on rapidly, and the vapor passes off through a long pipe which is all the time radiating heat. We can justly expect only a mixture of real steam with more or less mist. And if this mist, which has already lost its 500° C. [932° F.] of latent heat, is reckoned as invisible steam, our figures will not give the exact truth. 76 EXPERIMENTS UPON NON-CONDUCTING And then again, besides the two or three feet of pipe with the covering to be tried, there are necessarily the cap and other fittings which will lose heat in spite of any wrapping which we may put around them. The gross results, therefore, need to be corrected by the amount due to the condensation by that portion of the branch which is not protected by the covering. It is quite possible to find the amount of this correction, if one has the material of the covering so that he can apply it himself and make it uniform. Thus we may cover, say, three feet of pipe, wrap the fittings with a good non-conductor, and make trials enough to get a fair average. Then we may cut off one foot of the pipe and covering, keeping the other parts and their wrappings exactly the same as before, and make a second series of trials. Now, let x be the amount of con- densed water due to the three feet of coating, and y that due to the fittings. Having found for one hour x x by the first trials, and by the other set 2 x IT Xy=b ; by combining these equations we get ££=3 ( a-b ); and — -=a-&=condensation per foot per hour. o If cutting the pipe is not feasible, the deduction to be made may presumably be ascertained in another way. First, determine the whole condensation by the covered pipe and the w*ell wrapped fit- tings. Secondly, strip off* the covering and try the naked pipe with the wrapped fittings. Thirdly, wrap the pipe just like the fittings, and make more trials. Lastly, strip off the wrappings from pipe and fittings and try all naked. Now let x = the amount of condensation by the naked pipe alone; y — that by the naked fittings; z = that by the wrapped pipe alone; w = that by the wrapped fittings; and u — that by the covering in question. By the last determination above mentioned we have found x + y — a; by the second, x -f- w — b ; by the first, u -f- z = d ; and by the third, z -j- w = c. We may fairly assume that x : y : : z : w, or xw—yz. Then by the various eliminations and substitutions, we have : a(b — c) x — — - ; y a — c J a (a — b) ' a — c ? w (a — b) c m _ (b — c) c 9 a — c ? a — c ’ n — d — (b - c)c a — c In an actual trial, the result of which is given in No. 25 of the COVERINGS FOR STEAM PIPES. 77 appended table, the slag wool inclosed in straw board, supported by plaster rings at the ends, made altogether a covering 21 inches long. The extra pipe and the fittings were well wrapped with cot- ton wool, and the condensation was found d = 108.6 grams per hour. Removing the slag wool covering, it was found that b = 344 grams. Replacing the covering by cotton wool wrapping, it ap- peared that c= 105.3 grams. With all wrappings stripped off, it proved that a = 428 grams. Hence, substituting these values in the above formulas, we find a? = 316.7 ; y = 111.3 ; w = 27.3 ; 0 = 77.7 ; u = 81.3. Fig. 20. For making trials by condensation, I used the arrangement shown in side view in Fig. 20 : a, the main steam pipe ; b, a T by means of which the steam may pass freely through the nipple c and the elbow d into the branch pipe e with its covering f. A bit of India-rubber tube m, attached to the stop cock k, connected with the cap g , allows the condensed water — when the cock is opened a little — lo pass into the glass flask ??, without direct exposure to air currents ; d , g, h, and the uncovered parts of e are wrapped with cotton wool. The angle of inclination is such that whatever con- denses in d and c runs back into the main pipe a , unless it remains suspended as mist, and is swept forward. As to the question of mist, 1 see no way of settling it except by combining the condensation method, including the correction given above, with the calorimetric method now to be described. 78 EXPERIMENTS UPON NON-CONDUCTING The calorimetric method, besides being direct and absolute, seemed to me to promise a closer approximation to the truth than any plan used hitherto. To carry it out, the contrivance represented in Fig. 21 A and B, and Fig. 22 A and B, was provided of different sizes to suit different coverings. O Fij 21 A shows a transverse section of the pipe, covering, and a pair of calorimeters. Fig. 21 B gives a longitudinal section through the line M N of 22 A. Fig. 22 A is an end view of the calorimeter. Fig. 22 B represents the same as seen from above. The calorimeters are made of sheet brass No. 29, and are so shaped that when clamped together they may completely and closely include a por- tion of the pipe covering c. The tubey* serves for the introduction of water, and the subsequent insertion of the thermometer, which is re- tained in place by the perforated cork h. Another pipe in the bottom m serves for drawing off the water by removing the cork n. The glass tube r attached by a caoutchouc connector to a small brass tube in the end, shows the height of the water. The top piece d , to the inner sides of which are soldered slotted brass plates g , allows the wooden panel v to be swung back and forth on the brass pin z, to equalize the tempera- ture of the water. The perforated, brass ears x and the binding rods s , with the thumb nuts w , furnish the Fig. 21 B. means of clamping the two halves over the pipe covering. Thick wooden washers y give a chance to turn the thumb nuts past the edge of the slanting bottom. A different mode of clamping is shown in Figs. 23 and 24, the first being a view from above, and the other a side view. Here the pine wood braces h, held together by the bolts r, are distinct from COVERINGS FOR STEAM PIPES. 79 the calorimeters. This inode of clamping was actually used in most of the experiments, but the wooden braces were not so easy to man- age, and they were much in the way of the wrapping. For in use the whole apparatus was covered with cotton bat- ting put on thick and held on by cotton twine wound around in various directions. Cotton wool makes a good and cheap covering, but it takes much time to apply it. Latterly, it seemed best to try other wrappers, and for the sake of greater compactness the form shown in Figs. 25, 26, 27 w r as constructed. Here the long sheaths z receive the wooden rods a?, wdiicli are held by pins at one end and the wooden w edges w w at the other. A calorimeter of this form was surrounded by a box of thin wood made much larger, so as to leave a space about 1J inches thick all around the brass boxes — the pipes c and / and the top piece p, as well as the gauge cb projecting outside the wmoden box. The space was tilled with nearly two pounds of live geese feathers. The feathers make an Fig. 22.— A & B. excellent non-conductor, but they are rather expensive, and by no means easy to handle. 80 EXPERIMENTS UPON NON-CONDUCTING Then the clamping arrangement of Figs. 21 and 22 was tried, and a cover was made of three thicknesses of very soft woolen blanket sewed on ; this is rather costly, but it is, perhaps, the best wrapper to use. A wrapper of hair-felt was tried twice, but it was too ten- der to be used many times, and it did not admit of sewing on, but had to be held on with twine wound around. In making trials, the calorimeters are filled up with water 10° [50°F.], or 12°C. [53.6° F.] colder than the airof the room, the thermom- eters are inserted, and the water is well agi- tated with the paddles. The temperature of the water, the steam pipe, and the air of the room, and the time are noted down. Observations are made every half hour, or oftener, till the water stands 10° C. [50°F.],or 12° [53.6° F.] higher than the surrounding air. The water is then drawn oif and weighed. The experiment is re- peated times enough to give a fair average. Of course, all the heat transmitted by the length of pipe covering inclosed by the appa- ratus is taken up by the water, and could be exactly determined were there no radiation from the calorimeter itself. But wrap as we may, there will still be a loss when the surrounding air is colder than the water. To neutralize the error from this source we should use only that part of the experiment which lies between two obser- vations, in one of which the water is about as many degrees colder than the air as it is hotter in the other; thus the absorption of heat from without in the first part of the time is balanced by the radiation from within in the latter part. COVERINGS FOR STEAM PIPES. 81 The calorimeter itself takes up heat as well as the contained water, and we must therefore add to the weight of the water as much as corresponds to the weight of brass and immediate sur- roundings, the specific heat being taken into account. For every calorimeter, this is a constant quantity which may be determined Fig. 25. Fig. 26. practically by mounting the apparatus on an unheated pipe, wrap- ping it as usual. Cold water is run in and allowed to stand some time, the temperature being noted. Then the water is as quickly as possible run out and replaced by warm water of known tem- perature. After a thorough agitation, the temperature is ob- served, and the warm Fig. 27 . water is drawn off and weighed. Let t = the temperature of the cold calorimeter. t' = the temperature of the warm water at first. T — the temperature of the warm water after it is run in, and a — the quantity of warm water drawn out and weighed. If x = heat units taken up by the calorimeter, reckoned either in grains of water heated 1° C. or in pounds of water heated 1° F.; then T = ±L±la ; lienee * =■ * %~P a + x ’ T—t 82 EXPERIMENTS UPON NON-CONDUCTING In an actual trial, the water equivalent of the calorimeters A 1, A II was found to be 194 grams for each. In an experiment with covering No. 34 of the table hereto ap- pended : At 91i. 15m., A I stood at 12.63° C. [54.73° F.], and A II at 12.64° C. [54.75° F.]* At 3h. 25m., A / stood at 42.73° C. [10S.91 0 F.], and A II at 42.18° C. [107.92° F.]. Mean temperature of the air 27.7° 0. [SI. 86° F.] Interval, 370 minutes. From A I were drawn off 3,260 grams of water ; from A II 3,320 grams. Calculating from these data: (42.73—12.63) (3260 + 194)x J^=16.8o9° C. (42.18-12.64) (3320 + 194) x^= 16.833° 0. The average of these and trials made on two other days was one kilogram of water heated 16.671° C. per hour in each calorime- ter. But the two brass boxes include 14 inches in length of the covering. 12 Hence — X2x 16.671 = 28.579 kilogram-centigrade heat units, 14 & or one kilogram of water heated 28.579° C. per hour by each linear foot of the covering. To reduce this to pound-Fahrenheit heat 9 units, we multiply by — x 2.205, which gives 113.43° per foot per o hour. Thus we have an absolute measure of all the heat which is trans- * Though throughout this report many temperatures are expressed in degrees with two decimal places, it should be understood that these are not actual read- ings, but in most cases the observed numbers have been corrected according to the calibration table of each thermometer ; and in calibrating, it was thought as well to carry out the calculations to hundredths of a degree. COVERINGS FOR STEAM PIPES. 83 mitted by the covering. But it may, with some reason, be objected that the rapidity of transmission, and therefore the amount of heat passing off from a constant source in a given time, is influenced by the temperature and nature of surrounding bodies ; and hence that the communication of heat to a fixed quantity of water is not neces- sarily the same as that actually given off to air in free circulation. Further experiments are needed to determine exactly how the heat imparted to the water calorimeters compares with that given out to air by the freely exposed covering. We should naturally expect that as water has a higher specific heat than air it would induce a more rapid cooling, and that therefore the water calorimeter would give higher results than the condensation method. But we have a limited quantity of water allowed to get pretty warm as compared with an unlimited supply of cold air. In fact, the coverings Ho. 24 and Ho. 25. of the appended table were intended to be alike, and were very nearly so. As the temperature of the steam averaged 150° C. [302° F.] its latent heat was 500° C. [932° F.]. How the quantity of water condensed per foot per hour in Ho. 25 was 46.5 grams. And 46.5 x 500 x • - \ ■ — 23.250 kilogram-centigrade heat 6 1000 ° ° units, while the calorimeter trial of Ho. 24 gave 22.807°. The dif- ference is not large, and this tends to show that air-cooling and calorimeter cooling are not very unlike. Any uncertainty as to whether water calorimeters show the actual loss of heat by pipe coverings does not affect their comparative in- dications respecting different coverings. A more important matter, perhaps, is the not unfrequent impossibility of exact fitting. Cov- erings which are plastered on are never of uniform thickness, nor are they exactly cylindrical. In such cases the contact of the calorime- ters will be more or less imperfect, and radiation through confined air will be partly substituted for direct conduction. On the other hand, yielding coats, like hair felt, are somewhat compressed by clamping on the brass boxes, and yet more by the weight of the filled apparatus ; and the more closely fibrous matter is compressed, the greater its transmitting power. So the results of the trials are likely to be somewhat too favorable to the hard and inelastic cover- ings. In carrying out the examination of pipe coverings, it seemed best to get samples such that each one could be used for the three methods in succession. Accordingly, circulars were sent out re- questing manufacturers and others interested in the subject to fur- 84 EXPERIMENTS UPON NON-CONDUCTING nish whatever specimens they wished to have submitted to compet- itive trial. The directions called for pieces of ordinary two-inch steam pipe two feet long, cut with a right-hand thread at each end, and then covered, in the usual way, for a length of eighteen inches between the threaded ends. In response to this invitation, thirty-one samples were sent in by various makers, and eight kinds were brought and applied directly to our hot steam pipe in place. In only one or two instances have prices been given. The room available for the experiments is an iron-turning shop, through the upper part of which runs thirty-six feet of two-inch pipe, conveying to an engine steam of sixty pounds pressure. The engine is run, in term time, from 8.45 a.m. to 12 m., and from 1.30 to 4.30 p.m. During the noon hour the pipe is full of hot but not moving steam. Before entering the room, the pipe runs about 110 feet from the boiler. Two lengths of the pipe in the room were taken out and replaced by as many as possible of the two-foot sam- ple pipes coupled together. Hear the middle of a set was inserted a T with a three-quarters inch side connection turned upward. Into this was screwed a bushing furnished with a long thimble reaching nearly to the bottom of the T inside, as is shown in Fig. 28, in longitudinal section, a the T ; p the plug ; n the thim- ble, made of a piece of three-eighths inch gas pipe capped with c and filed thin. A thermometer t suspended in the thimble by means of the per- forated cork <9 gives the temperature of the pass- ing steam. Calorimeter and air-chamber trials were made, with each covering two, three, or sometimes four successive days. AVhen one set was gone through with, another set was mounted in their place. But several of the samples had been so covered as to leave too little space for a good grip of the pipe wrench, and therefore could not be dis- mounted in fit condition for connecting again as side branches. Moreover, the number of speci- mens sent in was unexpectedly large, some makers furnishing many pieces differing more in size than in kind. ITence it was necessary to be con- tent with setting up again for the condensation trials only such un- injured pieces as might represent the different types of coverings. COVERINGS FOR STEAM PIPES. 85 When the experiments with each piece were finished, the cover, while still at its maximum of dryness, was stripped off, dissected, and weighed ; for, of course, the non-conducting power is not the only thing to be considered. We must take into account the cost, weight, bulk, necessary thickness, durability, ease of application, ease of removal, repair and renewal, simplicity, appearance, freedom from smell, temptation to insects or mice, hardness, resistance to moisture, combustibility, liability to crack, and the possible chemical effect on the pipe. Pipe coverings may be divided into four general classes : 1. Those consisting essentially of light fibrous matter, as hair, slag wool, or paper, applied immediately to the pipe. 2. Those composed of a paste or mortar, which is plastered di- recti y on the pipe, in one or several coats. 3. Those having an air space next the pipe. 4. Complex combinations of different layers. It will be seen that of all the coverings tried, as shown by the annexed table, the most efficient was simple hair felt with a cheap cover of burlap. It appears also, that of the whole number, seven- teen owe their efficacy to hair. Slag wool came third in rank ; but it should be noticed that this was a most remarkable covering. The slag wool "was two inches thick and was surrounded by wooden slats one inch thick, these being covered with three thicknesses of cloth. So the whole was enormously and absurdly bulky. On the other hand, this wool was not of commendable quality, for it parted with 38 per cent, of heavy globules when it was thrown on a sieve, and this superfluous portion had increased the weight without doing any good. A more feasible covering was tried in Nos. 24 and 25, with the very same fiber after shifting out the shotted slag. This one-inch coating showed a fair result, though, of course, by long heating and sifting and handling, the fiber had become much broken, and could not therefore be as efficient as new wool. It was desirable to try new slag wool of the best quality, but the dealers in the article were unwilling to sell a small quantity. No doubt the best kind would give a more favorable result than that shown in No. 24, and would prove really more economical than the cheap sort. I suppose this latter kind is the same substance that is known in England under the misleading name of “ silicated cotton.” Spongy paper, as in No. 16, proves to be a tolerably good non-conductor. In a condensation experiment, not given in 86 EXPERIMENTS UPON NON-CONDUCTING the table, Reed’s covering gave a net result of forty-six grams per foot per hour, which almost coincides with that of slag wool in jSTo. 25. Straw covered with cotton cloth, as in No. 28, does not show an encouraging degree of excellence. The otherwise useless rice chaff of No. 18, moistened with water- glass to make it less inflammable and somewhat coherent, proved much more efficient than straw rope. It should be remembered, fibrous or porous matter acts mainly by virtue of entrapped air, and hence the looser it is the better. Thus everybody knows that hard-spun woolen stuffs do not make warm clothing. Asbestos is commonly supposed to have wonderful virtue in resisting heat, but there is really no magic power in the mineral fiber. It is a non-conductor only when it is in a light, downy condition and full of air. The figures given in No. 50 show that hard-pressed asbestos paper conducts heat very readily. And it was observed that in those cases in which asbestos paper is put between the pipe and hair felt, the asbestos fails to prevent the scorching of the hair. Incombustibility should not be confounded with non-conducting power. As to the second class, the plastered coverings, none seems to be worth much except the diatomaceous earth or “ Fossil Meal,” of Nos. 21, 26, and 27. Of only one or two of them was the exact composition known, but there is not one of such excellence that the secret of its composition is worth keeping. Most of the pastes have an admixture of hair, vegetable fiber, or asbestos to make them tougher and keep them from cracking. The more organic fibrous stuff which can be worked in the better, for it makes the covering lighter and looser, and hence less capable of transmitting heat. When such fibers are surrounded by clay, plaster, or other mineral matter, it makes little difference whether they are of themselves combustible or not ; they cannot char or burn unless used in connection with steam of extremely high pressure, or superheated steam. So here again, as compared with animal or vegetable fibers, asbestos, which is really a heavy mineral, has more plausibility than positive virtue. Most of the makers of plastered coverings appear to have been ex- perimenting with materials which are too dense. To the third class, those with greater or less air space, belong Nos. 9, 12, 19, 20, 22, 23, 34, and 37. With regard to the efficiency of coverings with an air space, the experiments so far are not decisive, because in no two trials was it COVERINGS FOR STEAM PIPES. 87 certain that the material was otherwise of precisely the same quality and thickness. In Nos. 34 and 36, which were apparently the same, with the exception of an additional wire gauze support in No. 34, the air space showed but a very slight advantage. The comparison of Nos. 16 and 19 is even unfavorable to the narrow air space. But when there is no visible covering at all, as in Nos. 47, 48, and 51, it makes a wonderful difference whether the calorimeter conies in direct contact with the pipe, ora thin stratum of air inter- venes. It seems, too, that a quarter of an inch of air is as good as an inch. This calls to mind the well-known fact that one may safely stay a few moments in the air of a room heated to a point much above the boiling-point of water, as in the old “hot room ” of calico print works ; but if the skin touches a metallic body or a liquid of the same temperature, burning or scalding ensues. So it was also observed that when hair or paper remained for a considerable length of time in contact with the hot steam pipe the organic matter became browned or scorched, while the hair felt in No. 9 remained, to all appearances, entirely unchanged, except at the ends where it was gathered in and touched the pipe. It might be thought that the bright tin plate case, as such, had something to do with preventing the scorching ; for, from the tradition of Leslie’s old experiments on heat, a surface of bright tin is reputed to be a poor radiant and recipient. But when the mere tin case of No. 9 and the straw-board case of No. 20 were put on the pipe, side by side, the tin box soon became hotter than the hand could bear, w'hile the straw-board could be handled. An air space, then, may prove very useful in obviating one of the great objections to coverings of organic fibrous matter, though it is not specially beneficial in other respects. Woolly asbestos, or asbestos paper, which the makers of some of the specimens appear to have relied on for this purpose, does not accomplish the object, for in all those samples in which a wrapping of asbestos came between hair and the pipe, the hair, after the trials, was found to be discolored by the heat. And then again, experiments Nos. 47 and 50 show that a wrapping of asbestos paper does not in- sulate so well as the same thickness of mere air. The popu- lar confidence in asbestos partakes of the character of a supersti- tion. Coverings of the fourth class, those made up of many layers of 88 EXPERIMENTS UPON NON-CONDUCTING different kinds, have not proved better or more efficient than the simpler ones; and we may justly set down much of the ingenuity shown in devising coverings of this class as fruitless. Of course, complexity enhances the cost, and there should be some corre- sponding advantage. But of the actual prices charged, I have received statements in only one or two instances. It is evident, however, from the labor necessarily required to produce some of the specimens, that cheap- ness has not been kept sufficiently in mind. The question as to whether a covering shall be used or not is one mainly of dollars and cents, and the inquirer must be satisfied that the saving of heat will soon make up for the outlay. From Ho. 51, it appears that a naked two-inch pipe, carrying sixty pounds steam, may condense 181 grams per foot per hour, and Ho. 25 shows that a cheap covering may reduce this to 46.5 grams, making a saving of 134.5 grams per hour, or 1.345 kilos. = 2 .96 lbs. of steam in a day of ten hours. So the covering of one hun- dred feet of pipe would save, in a year of 300 working days, coal enough to convert 88,800 lbs. of water into steam. If we consider one pound of coal as capable of making 8.88 lbs. of steam, we shall have a saving of five tons of coal per year for one hundred feet of the covering. So, where coal is worth $5 per ton, it would cer- tainly be worth the while to use a covering costing not more than twelve cents per foot, but we might wish to think twice before taking one worth twenty-five cents per foot. In. some cases it may be worth the while to add a little to the ex- pense for the sake of securing a good appearance and having a cover- ing 'which can be easily kept clean. An encasement of cotton duck or canvas looks well, whether the cloth is drawn together by the edges and stitched, or is torn into narrow strips and wound around spirally. Except the costliness of this closely woven stuff, the only objection to such a jacket or bandage is its combustibility, and this ought to be obviated by painting the canvas with water-glass. Some of the plastered coverings sent in have a hard, smooth exterior finishing coat, which gives a pretty appearance, but adds too much to the already excessive weight. The weight and bulk of a covering are of some consequence, for if we add to the pipe three or four times its weight or size of other matter, we make it troublesome to support. A coating over five inches in diameter for a two-inch pipe seems absurdly disproportion- ate ; and as the pipe itself weighs fifty-six ounces per foot, an ad- COVERINGS FOR STEAM PIPES. 89 ditional weight of sixty ounces or more is altogether beyond reason. The weights given in the table show that some makers have sinned grievously in this matter. In the large and heavy specimens tried, excepting No. 3, there appears to be a lack of efficiency, and there is little else to commend them. Of course, for every kind of covering there is an optimum of thickness beyond which the cost and bulk of any addition is not compensated by any further gain in efficiency, and this best size can be approximately determined only by a series of careful exper- iments with each particular substance or composition. As most of my trials have been of ready-made coverings furnished by others, there are few data for reasoning about the matter of thickness. In comparing Nos. 1 and 2, we see that an increase of hair, beyond an inch of thickness, or thirteen ounces of weight per foot, does very little good. Nos. 27 and 35 were made with the same fossil meal paste, and put on by the same person ; and here we see that a much less thick- ness than one inch of fossil meal is insufficient. Though Nos. 3 and 24 are not strictly comparable, the two taken together go to show that when poor slag wool is used it will pay to have it considerably more than an inch thick. As to ease of application, repair or renewal, Reed’s covering, Nos. 16 and 19, and the Chalmer-Spence Co.’s complex tubes, Nos. 6, 10, 12, and 17 stand foremost. These are molded into form and, partially bisected lengthwise — Reed’s so as to leave merely a thick- ness of paper for a hinge, and the Chalmer-Spence through one side of the hollow cylinder — so that the tube has only to be opened or sprung apart somewhat, clasped over the pipe, and fastened to- gether at the meeting edges with double-pointed tacks. The cover- ing can be taken off at any time by taking out the tacks and pry- ing the joints apart. Next to these comes hair felt which can be cut of suitable width, clasped around the pipe, and held on by winding string or fine wire around spirally. It may be left so, or cloth can be sewed on around it. Stra\v rope can be wound around spirally at a pretty rapid rate, but in time it becomes so brittle that it is worthless when unwound again. In No. 37, the tin plate cylinders are made in halves which lock together and are more easily put on than taken off. The inner case is held off from the steam pipe, to make an air space, by means of short corrugated tin plate rings. 90 EXPERIMENTS UPON NON-CONDUCTING The tin plate case of No. 9 is made in one-foot lengths, with two opposite longitudinal ribs projecting inward. Each length is made in halves, and the ribs are formed by turning in the edges so that they come double when the two halves are put together and fas- tened with solder. The cylinders are so joined end to end that their ribs lie in planes at right angles to eacli other. Both this covering and No. 37 are lacking in simplicity and ease of adjustment. The air space in No. 19 is made in a ready way by winding around the pipe narrow strips of asbestos paper, some distance apart, before the covering is clamped on. In No. 12 the complex cylinder of hair and pasteboard is held off from the pipe by short, thick paper cylinders. In No 20, the air space was made in a cheap and easy way with rings of plaster of Paris placed a foot apart, and a cylinder of straw board sprung on over them. This straw board had been shaped by rolling it in the machine with which tinkers form stove pipe, and was made large enough to have one edge lap over the other a lit- tle. The plaster rings were made in halves, with a groove around the outside to receive the string with which they were tied together on the pipe. Such rings can be cast with little trouble, and they should be well dried before using. They could be made of porous terra-cotta at trifling cost, and it would be better to fasten them on with small wire. The half rings in No. 22 were cut out of thin pine boards with a scroll saw, and the straw board was tacked to them ; but pine rings shrink and become scorched, while those of plaster or burned clay are hard, incombustible, and poor conductors of heat. The case of No. 24 was made in the same way, but with an incomplete cylinder of straw board, so that there was left, along the whole length of the upper side, a narrow aperture through which the slag wool was crowded in. The long aperture was closed over with a somewhat wider strip of straw board, the whole being finally held together by winding twine around. Fig. 30. COVERINGS FOR STEAM PIPES. 91 I Fig. 31 . The rice chaff of No. 18, the sphagnum of No. 22, and the charcoal of No. 29 were put on with the help of a wire cage specially contrived for the purpose. This is represented in Figs. 29 and 30. The wire gauze b is turned at the edges around the long wires e , and is tacked to the wooden supports a , g. The boards c , perforated with the holes d , are placed on the top of the pipe, the wire cradle is brought under, and the loose wires e are slipped through the holes d. A sufficiently wide piece of cotton cloth is laid in the cradle, and the hangers c are raised up with wedges till the cylindrical part of the gauze is parallel with the lower half of the circumference of the pipe. The filling is now crowded in around the bottom and sides of the pipe, and heaped over the top ; the edges of the cloth are drawn together, basted, and then tightly sewed ; the hangers are finally slipped off the ends of the wires, and the cradle is taken away to be moved on for making another length. With a little care the cloth edges may be drawn over so as to make the upper half of the covering cylin- drical. The cotton cloth used was of the cheapest kind, costing about one cent for a foot of the covering. Of course, a cradle of sheet- iron or of wood could be used, but the wire gauze allows the free escape of any vapor that may be formed during the application of a moist filling to the hot pipe. It requires some practice to put on paste coverings with a trowel, and it is by no means easy to get them uniform and round. With the exception of the fossil meal, the plastered coverings are worth- less when they are taken off. I have observed no chemical action by any of the coverings, ex- cept such as contain plaster of Paris, which, while wet, rusts iron rapidly. The corrosion of pipe, which is said to have occurred some- times with slag wool which had become damp, must have been caused by the sulphate of lime formed by the oxidation of a trace of sulphide of calcium in the slag. Respecting durability, little can be learned by trials lasting only a few weeks. But it is well known that animal and vegetable sub- stances undergo a change by long-continued heating, and this some- times becomes obvious even after a few days’ exposure. Wool, hair, cotton, and paper in contact with a pipe at 150° C. [302*F.] 92 EXPERIMENTS UPON NON-CONDUCTING soon turn brown, and have their elasticity much impaired. To he sure, it is only a moderate thickness that becomes so affected, and samples of old coverings which have been sent me show that it takes years to scorch any considerable portion of the whole depth. Straw suffers farther out than the poorer conductors. Specimen No. 39, which was said to have been in use nine years, was still bright and straw-like outside, but the steam pressure had been under fifteen pounds. The straw alone in this sample weighed 4.2 ounce s per foot, while the new straw of No. 28 weighed 10.6 ounces. If No. 28 really represents the original dimensions and character of No. 39, as it was intended to, the impairment of efficiency by the shrinkage bears a strikingly small proportion to the loss of weight. The change of organic matters by a steam heat is too slow to produce any sensible odor, but if by any chance hair felt gets wet while on the pipe, it gives out an unpleasant smell for a long time. I have known instances in which this proved so great an annoyance that the covering had to be stripped off ; and the possibility of such an occurrence is no slight objection to the use of hair in immediate contact with the hot pipe. The intervention of an air space offers a possible prevention of this trouble as well as of the crisping of the hair. As to the chances for spontaneous combustion of any covering consisting of vegetable fiber, it is difficult to pronounce with cer- tainty. There is a report in circulation that a certain paper cover- ing has taken fire of itself; but I believe this is rather a matter of interested surmise than of positive proof. I put two pieces of the indicted covering on a pipe near the boiler, where the temperature was very high outside and at least 150° C. [302° F.] within the pipe— one of the pieces as it came from the maker, the other charged with cotton-seed oil (this oil readily induces the combustion of cotton waste), and yet both the paper tubes remained so exposed to heat for six months without showing the slightest inclination to take fire. Of course, coverings made of organic substances become exces- sively dry and tinder-like when they are constantly exposed for a long time to steam heat, and then they very readily catch fire when a spark or a flame touches them. Therefore, though there is little danger of fire from within, it is well to guard against fire from without. The impregnation of cloth wrappings with borax, tung- state of soda, or water-glass is calculated to lessen very much the danger from fire. In connection with the testing of what were offered for fire-proof COVERINGS FOR STEAM PIPES. 93 window shutters some years ago, I was led to believe that one of the best and cheapest non-conductors could be made of water-glass and wood charcoal, since, by charring, all gas-forming material is eliminated from the wood, and carbon does not oxidize rapidly when covered with the varnish-like and fusible silicate. It was this mixture that I tried in No. 29; but as there was no light pine char- coal at hand I was obliged, by want of time for making some, to take a rather too dense substitute. Still, the result is encouraging, and I hope to follow up the matter farther, for this concreted unin- flammable coal is capable of many useful applications. The rice chaff in No. 18 was also mixed with enough water-glass to render it somewhat coherent when dry, and as the chaff is itself rather silicious, we thus get a covering so charged with mineral mat- ter as to be hard to set on fire, and at the same time quite light and efficient as a non-conductor. Doubtless chopped straw might be used in the same way. But sawdust soaks up so much water-glass as to make a paste that dries too dense. Coverings that contain flour or meal are liable to be troubled somewhat by mice. Even silicated rice chaff* is not altogether proof against them. These animals also gnawed the interior of specimen No. 12. When it is desirable to have a covering w^ater-proof outside, this can be effected best by putting on a wrapper of sized cloth and applying to it one or two coats of oil paint. Of course, this should be done only after the covering has become perfectly dry. But trouble is sometimes caused from within, by leaking joints, and in such a case a water-proof coat only occasions a spreading of con- cealed mischief inside. On the other hand, a very porous coating allows the vaporized water to escape, and, if the leak is slight, no harm is done. It is well to use a pretty loose material for covering the joints, to separate those parts from the rest by impervious dia- phragms of tin plate or plaster, and to make them so that they can be easily removed without disturbing the other portions. The following table of specimens tried, Table I., is arranged in the order of their transmitting power as shown by the calorimetric method. The first column gives the source from which each of the samples was obtained, together with a concise description of the make-up, beginning with the coating next the pipe. Those marked “ J. M. O. ” were home productions. The maximum diameter is given in the second column, few being quite cylindrical. 94 EXPERIMENTS UPON NON-CONDUCTING The weight in the third column includes the average of the whole of the covering, but in many cases the essential part constitutes only a moderate portion of the whole weight. Fuller details of the structure are given in the second table. The fourth column gives the highest temperature observed in the air chambers during the trials. In one or two instances the covering was so irregular that the air chambers could not be made to fit closely enough for a fair trial, and so no figure is given. The numbers in the fifth column show the condensation by each foot of the covered pipe in one hour. u Gross” signifies that the condensation by the fittings and extra pipe is not allowed for, and the figures given are therefore really from one-fourth to one-third too high. The method given above for eliminating this error was not invented till most of the trials had been made. In the trials made latterly, the word u net” shows that the proper deduction has been made. It takes many days to get the data for the requisite correction, and it is hardly worth the while to spend the time for this, with many samples, till further careful experiments shall show whether the matter of mist really vitiates the results of the con- densation method as much as we may suppose it can. The sixth column shows how many heat units are actually trans- mitted in an hour by one foot in length of the pipe covering; that is, how many degrees Centigrade one kilogram of water may be heated by it, or how many kilograms of water may be raised 1° C. In the last column the same loss of heat is expressed in degrees Fahrenheit which one pound avoirdupois of water may be heated. As all the samples beyond Ho. 30 allow more than twice as much heat to pass through as is transmitted by Ho. 1, it would seem that in Ho. 31, and all after it, there is much room for improvement. The average of the 46 coverings — Ho. 50 being left out — is 24.623 kilogram-centigrade heat units transmitted. The average weight is 49 ounces, or a little over three pounds per foot. TABLE I. COVERINGS FOR STEAM PIPES. 95 o f? & X CP o GO 05 iO r — | ^~H 05 ©i to i> fi D HH CD 05 o CO o CD to o to to OS o lO t> O t- i> 05 CO 05 to oi 00 CO 05 J> ©5 05 CD O CO Safe 1 C s iO iO iO CD CD CD CD CD i> t- K E- £ © HZ* ©5 05 to 00 CO ^H GO U ^T-l 05 CO 05 i> o CD i> Ot IO O GO 05 TF o o i- O i— 1 IO 00 KIL( HEA FT., 03 Tf id id id o i> £> i> 1-1 i—i ’ rH 1-1 r-1 t-H i-H 1-1 1-1 K § O g §** « Q „ CS otz o * M M * S s § S 5 a si CO 1*0 ■r-H CD o 1 C GO 00 CD o O 05 i> 00 05 id id 00 i© ©3 T-l 05 lO CO H* o o iO ID lO CO CD 1*0 ©3 00 CO CO r-| 05 00 i> ©3 „ CO id 05 i> o 05 00 * o* A id CO T — 1 ©3 TH CO r~l •—1 ©3 ©3 rH IO Si 5 2 N W ^ CS SO H © P- 3 1 g . 02 -ca © .*7 2 . P-nJ I ~ I W -* P iS'oS I g ® § © H bcfc .2 w a* h 3 ~ W S £ > o 7-3 © S 4-1 o CL • «Ph pH . 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P3 CC O *^0 . -o 'p S o'O T3 CD C , r— < £h 02 W CS fl © a CO c3 O ^ O o © S S5ZJ *- » -° 2 S 53 . ’SHa ~’ OQ ■ u AW 02 § O H P 3 +3 hj) 82 CC 02 hh ^< 1^0 CC _ OJ •, (D HH CD W P- .rP # P2 . - ■ o 3 A J2 ^H ._, HjJ ,_, '■« g * ‘ o 02 © © M 1 C 3 « ©' o o o fc ^5 ^ oooooooo ££££££££ TABLE I. — ( Continued .) 96 EXPERIMENTS UPON NON-CONDUCTING ◄ £ o b z a ft*- K O r q B B C a h B TH o »o CO to 1-t i> o 00 co o C30 00 co 00 00 rH ot C5 CO o 05 o 00 t-H t-H ▼B 05 00 o o cd 00 05 d oi CO to CO d £- i> t- t- £— 00 00 00 00 00 oo C5 K ilo ig“ $5 r « B H A S B CO CQ O 05 Ci CO C— OJ ^ ® to H o t> c* o GO 00 cs 05^ B g g Z < B’-' - q o o H r g © B PS S t» g « g £ B SS" gg* B £ ° fe B B _ P 3 o H S W B pj S O pq 5 8 i © &c-q C 02 -- C3 S-, o> — cS o *- e 3 I 3 > I c/j‘3 > Pjp fl c q •= §q a — SJ r— 0) X! q o © * a Cfi rrt CQ 03 £ w 02 21- 03 o rt . © q 9 gd g -£ M , 03 5 02 03 ,© 'z ~ K S B 03 o §.„• 7 * ® ^ 8-5 a -O CO M S<3 > -qq I fc+“ g 0^0 02 _02 T 1 <« © I _LJ C- s- o 2 •2 I u 5 o •g ffaS^ ?r op 5 — © • |-s 02 r — B £ tT 02 ^ 9 o <“ P5 ® q-B' ) «T3 m q- . & ® c^O © > . 8 I jp g J2 oo <5 ^ a <1 t-h ^=2 p - § “ $> 02 ooj) •g ® ^o* *p _ Q O 0 02 ~ 1 .J 17 ^ P.S5 * .OB rp 02 e3 O ^ ^ S © s at 2 2-3 IrP, -go ”r^ rH 0 “o' © • © © H «» ♦f « £© . B tPosdo-:—' 02 TH <5 (M <1 C50503050T-l50i>i>OJT-!C5 '"^« 00 0 D 0 Seol> 00 S 0 i>*i*'ti 0 C 5 '^'^OC 5 TtlOTHlOGOAOOi-IOfO?^i> 05 ^-' 0'>COTt<'-tf50f>»?>aOGOCOC505©©^HCOSOi>05 03 ©3 ©3 03 ©3 ©3 ©3 ©3 ©3 cm ©3 co co co co co co co 55 . 00 gross 47.00 gross 74.00 gross 61 . 00 gross 79 . 00 gross 10 ao O 0 ■ 00 ■xt 03 t— 1 1 O 00 00 00 CO 1 CO 50 ) 03 * ^ 03 0 0 > CO 05 • i> 05 50 50 50 50 !> *> ia i- t> i> i> O 05 05 t-h O CO ©3 03 05 O O ^ CO 03 CO 05 GO lO T-l 50 05 GO 03 05 -to -to —to -to «H< -It* -to -h* — h* H°o ^ -H «H< ^'-^'^HiO'^iOCOiOlOCO'^^iO '^10 101050 '^ tc S Q © s © 13 h w © o g a i o _ T3 § as — M u -8« 02 * 0 ) =3 «<$i H-5 cs ^ a *^ OnfL, O _ ^ i-h n S*H a^ £ ^ '£ ^ 'S • . © . © a o go a . . M .02 50 ,° i> r O 00 03 03 fa ©< a © S © r> C! ■—< 1 I ?a o «u 02 . •5 * «3 2 Ph 3 «w 2 O ^hCh S 02 © S' .^*05 S J • X O O cs H J 'GO (C , -• 2 » . 3 02 ib S’ * ? .3 K* ^ ^5 ►— I Q* -M HdS g ,0 © O (D r , h .. —g-gS &BQ J 3 o fc : m H © - Ch © S 2 iS&tzZ ■” ° 2 « a « b © g =3 2 ;^ 5a « -iS S 3 O as — . o c u 00 *C © ^ r© 6 o H O w Ph • 02 © 1-3 p* £ a w h*J © rj S ;5 ^ fa ^ g ^ “ © Q »S Jill S § .a « ■a F « h j? a • rt co £ | a M "d I 0 • § fc t- O M dg ^ ■ — <1 CO ■ © <(H ^ © >-5 S © _o 3S >»(— : tc ; .3 & ^<1^Ph 53 II 8 tfl M o . O o^. ^ .O *02 <- cc Szi h f> W „JS B-S . 4-3 C 3 m • f-t j© ^5 a3 <5 -< O O O O o o S3 ^ ^ ^ ^ £ oocooooo 000 ^ 98 EXPERIMENTS Upon NON-CONDUCTING CS pj w g P 0 <«o CO 03 OS 03 O 0 CP O 03 t- T—l CO* tH IO © d OO d co t- cs 0 0 03 10 g S £ 1-1 1-1 03 03 03 10 Ph ^ « c* » p 0 os f- O tH 0 § 5 ~ i_— os T*H O 03 i— CO 0 p 0 0 03 TtH CO 00 g 53 _ -r—l CO OS d *—< O 1 i-MH W X fa Tf 10 IO IO cs CO t-H K 00 00 tH 1 H Ph p £ S 2 M 0 0 00 00 X a a <• r H ° i~ i> t> 0 . E- > X 0 ^ 05 00 03 0 p ^ os 1.0 W BJ O J> os 0 £ W > P 5 t-H 1 1 •clto W Q2 H®* «h# - .n 03 new ^ O a O iO 03 03 > I b€ 03 > O U bO C • rl • -4-2 ■*2 . O 2 © 0 ! ^ « * o. o C3 c S 8 O x O £ •so g £ fiSB IsJ ^ „ 4 £ P*. ^ p ' 0) p- . g O V • !■> o o o >5 M Ph s (> „ O 03 H t! 3 bo g £ H ^ CC ^ si > s es *-i «*■* • ^ W £ W £ d .x .x . io JS 'o i2 ^ ^ co©oi©i>'#©©r*ic©oo^o:©eoooo(MO} Tjl©OOr-MnOOPPO®10i>0-lT)l©ffiOOIO>>IO^i>'HrH CP CD CO t— C— £— C— t— £— C— OO 00 00 05 OS 05 05 05 O © t— 1 ©3 ©i CO CO l-H t— 1 r— 1 rH T— t 1—1 T-l Weight per foot in oz. av. i> ©J 00 30 t- 1C O © IP t— O i>" i— I CO CO ©? C— O i— i CO OS CO CO © ^ 55 ©i>©-HH05t>^t>rH©HCOOOQO ?> WrldHHMH rlrlHrlrtrlCOrJ tO ©J ©i lO Diameter in inches. .01® 5^J( -HlCO rH|-^ ’-'1'# ,— —to C» — l(* HtC <— <|C0 rota) H® H 30 OOl^ H5|00 ^00 Ml® ohI - ^ H» iO'^lOiOlOiOlClOO^OiOiOiOiO'^lOlOCOiO'^H^'^'^iO Kilo-Cent. heat units lm. 1 h. © t— 1 © ©5 rH £— CO CO 00 OSCOCSt— hOOHCOt-hCOi— i©Tt*CO©iPlO MiO©0©^lOi.'MOlOOrHTiQOiOC')lOXQO 1010©i0©©©©©©£— £>t— C— t-t— 00300000©©©©© Weight per meter in grams. r>oo^©©oo© oo t- oo ©■» © t- t- ©c» co ©> co ©> oo © ©©?CO©C-©T-i 0©?l©)©t-©10©CO©J'SHTHi>00 ©7 ©5 ©J © CO CO ©i i — 1 ^©lOCOOiiaCO^fOO©^©^© © ©TtH r-Tr-T t-T CO t-T HHH t-T t-T r-T 00 CO ^ ©T ©T US Diameter in Millim. © — ^ © CO © CO © © © C'>CO©©©OtH{> t— ©) © t— I oo ©■> ©3 © CO©5COCOCOCOCOCOCO©COCOCOCOCO©3©i©i©©'r-l©©©CO T“ 1 TH T—l 1— 1 1— 1 1—1 1 — 1 1— 1 1—1 1— 1 T— 1 1—1 1— 1 1— 1 1—1 1— 1 1—1 1—1 1—1 1—1 1— < i— 1 1— t T— 1 ©i O M £ O) 'o' 00 X §3 O C C 0> © to CJ © O 'g £ Ijj © £ be** cS P .g +J ~ — “3 *c Ph 'd -pr Z'o 9 °* o i a £ 3 ^ J2 C/2 rr <« © 00 M >-. O © - faCQP be b (3 © f_ f-i . 9 .2 v © ’s 8 ’3 § £ 9 © 8 Jj -a g «r «r 8 g s S '« ~ Ij S* £ ^ 2 ai .JaS O g 2 £ 0 o •£ ® 50 CJ « Pi - © © © © O O 1 © c cs te k ;' p, Co © ■ 2 - ^ O-H ^ o © § .2 . £ ■gaa S 8 rM JO ^©5t! eS u CT 3 © © r> O 'H - £ S'O C p |.c g g w g £ ^ -t^> c3 ® M £ X bo P- .5 t. nca ^ ° p Ph 2 s - OS © ® S,® §■“ == .2 «1“ S 2 Ph P- P 8 g ts © © © © co aT £h S~ S- 5- c 3 cS eg cj ® fci Si t~, © » j_, o-o -u +j ya M 50 X m „ „ „ „ © © © © © ."2 "2 be a p “ *> ’g 2 aS O s X* o ^ g § aT to co o S ° - c: p ■ |-1 © © © _ .2 >, p 2 -2 2: C* p © as aS aS .. Ph Co Co C. _ CDKMtO^^g p p £ 5 £ P 2 <| «J § 8 $35 TABLE IV. 192 NON-CON DUCTING COVERINGS FOR STEAM PIPES. 1000?OC500^CSOHlC®IOOC500iO 00 ® i> ® O M «>§«! a -a' e$ '^C5©5'^IO3-r-IO3GO© COOOOt-i-HOO G-2 i-i Q> £ L, O G b*^'^®®Tj -j- S to S;r: i gi p^.s o &0005HHO00b-^^t-(SCJ00HC«rH® OWOroTLOCJOCO^fflOOCT^COWrH OOiffiOO t> 50 Tfl we: CO 05 i© H 03 03.^05 r-^ TH t-T r-T t-T r-T tH t-T 03 tH 1C ©3~ 03~ CO r-T 03~ of t-T t-T iooow^oncoco Wr-O00i>©10-H H C5 CO_ 03 1C ©3 00 CO 03 I-H tHtH t-T rH ccf 03 ^ © u P os - © P. T" - © ^ l" •s - XI a - co a rrt 2| g CC d Ph uj : © . -4L> CO © . 0)rn ^ CO © - CO 4J Cj — H © H.H . © '© P-tfH J3 . 2 "P oj Ph.E CQ Hi Oj ^ (—TH-i © Oj - /-n 5r. n - 2 CO 05 © _ p-.E a ft p- ^ © P- ei s 5 CO ^ J 5? CO +3 O oT w &0 II 3 P rj W)' - ^ o S «3 © ® (U S -S P fj g>g« »> Q^.rH CO CO P- Pc *- > - 3 rSvr'5 -S g.*§ 2*. ?•* - ° 8 p. bO „ © -P - .j: 3 i S CO © ai O® l © O t . .3 cq a coiCi^id© i ri 03 03 03 CO 03 CO 03 03 NON-CONDUCTING COVERINGS FOR STEAM PIPES. 193 O'^O'^t'OCOCOOOW'^OiOlCHt'T-iOJCDOOWt-OO'^tMQOH^iOXO'^M -Tt5l©OTH050il0 06i>O10J>'^ai00C3-r-iC0J>i>^C0C©00'r-lC0'rHC0C0i>C0C01010 W050i>t>i>Oi>OOOCOQO©0£-i>OOOiO«CO«305MQ003aHHO^lOO 1— I 1—1 05 1— I rH t— I H 1— I 05 rH 1—1 T-i 1—H T— t T-* 05 CO QOt-Oi>lOC5i>iCi>THT)(l00 50WOffi 00 ■ '^T)Jc50^ 1 -lo5i>ffl’i>000«OC'. 0-00 rHi-lT-1 WTjH«TH nrH 00 05 W W 05 C005C0t-C3Ci©^©TH0505 NH^OHOH-^M^OSIO C0'^iOOC0 05'^00C005t-C0 10^40101005 05 10 IO LO 05 05 *C t- 10005 i> 05 LO lO 05 OOIOIOO W05i>CQ«rHC05 £— 05 t— l .— 1 £— CO t-IOH 00 JO LO 05 i> 05 •^05'=tilOOlOCO»C10'^»0»OiOOO'^'rriTTiT^iO'^^05lO»OlO'^'^'!ti»0'^'^iO'^'^ fflC0®01HOlcaiHHOO10©H0310'^C0OQ0rHC0b‘10J> 05 ®t-©MC0ffl-H!>TflO^N001O05I000 J> l'* © rH o O iH O) IO O 00 M IO OH^ ^ 00 i> COOOi-l©05GO'r-l©LO*0£~OOl©{'-OOi>© t-T t-T i-T CO CO 05“ t-T r-T t-T 05" 05 r-T tF 05 i>C5C5i>e>-05COCJC5'r^«OCO OOTW^OOHOOIOOCO ^ 00 CO CO 05 lO 00 1-H O i> co co CO CO to to 05 05 ' CO CO CO 00 J> £> I I Q0W5HC0C0OCTC0NHC0OOI0H05HTjlCN05C0f'l-OHQ010i>'^T((C0THQ0 O £— 05 CO CO CO C5 CO 05 05 00 CO CO 05 ri O 05 1 — ' CO O O £— 05 05 CO 05 C O 05 i — 1 i — 1 CO 05 O bo *•2. a P % s J. •© s-a _Ph IS - o a 03 © §1 9*W T* t-T'P 0 5 5 bi) ^ 2 £ fc * J cfi © m & S.S'g 00 *r .5 ec -3 Q-© ® co . © © 03 B © a-« tf - © - S-i •*— * •3 o 53 -^O0Q £ S S * B « aTtB ; c3 O c3 o &. o bfi be 0) 'o 33 d. F-l 03 B'O S © P P «2 r S-S v* r ® bt^J 3 cc 00 „ *a§ ►.j _ a © o j3 u .5 « h h cS ^ bn P ^ < m m 5 2 ; i’l 53 p p* P 1 *p° S J 3 C P “111! ^ 1—1 rP 02 co © >• O 05 ^ - » 2 ?l -si tn — © 03 g 03 i'l » £•■3 £• © ^ © 03 O CL - 5©“ P- 05 a o o ej © S4-, «*H c o - ia ££ Si 3 £ " u w h to W to •-> 03 C3 a 03 03 00 ^ <» 0% °» ^iC3 CO rii ^ <0 05 CO ‘OiOO 00 g SO Cx?) © t- ^ © o C5 -Q0rH10H(Ml>i>OH05J«®(X)WCiiMI0J>O©©^X05OMt0® rj<10i>i>®OOQOQOCJ05 05 ® 0030 © 00 ©HHTHrHrHHNWWCt ’“I t — 1 1— 1 tH rH T“l 1 “ I T - 1 T— 1 T— 4 1 “H T— ( t-H 1—1 T~t Kilo-Cent. heat units 1 sq. m. 1 h. H^^O®OT}UOO?l>rHHCOiO^TH^iOOOt-OO^OSOrHNH^ Q!>MlCC5Mi>00Oi>mf'H©N05-eDNQ005OOOC0®)0OM Wi00SOrHNK)M^'^10i0a©i>b-Q0 X 05 05©OH0JCJC'(C0'^'^ T-irHTHWcmotNWWNWNWOiCJWNWWWMMCOCOeOlMmOJ Per cent. solid matter. OOCOt'POJNOOrieOrlOCOHO^fiaQHOOeOlOMOJH rHrHrHHCWQi>CS^^Q01©ICQOMW^OOi-lC)H«Jodci^CO tH ©* Net Specific Gravity. fc© OO 1© 1-1 00 tH 00 ’—I O ’-H t-h 00 O t-I 00 GO -r— 1 GO rH 05 lO CD CO CO 10101C- CO ~ - - - IOCOiOOi>MCOlOi>MlOIOCOlOO'^i©C(tWTlH rlrln H Hr-lT- l rlHiHrlH'HrHHrlTHHiH-Hrl03MrH Weight . in 1,000 c. c. QO»i>^HT)(GO©Ot'»lOlO©!>©100WOOOeOtHOi>©000 10lOQ©COO©COOOIO©®©iOJ}OT-llCHCO©i>©000©®0© rHHT-KSi>0>«OrH©10 3'ti00J^'^C0^«Hm)(J?rHCQi>C0t'©'^ t— It— i -r-l t—I ©< "^ i— 1 t-i Thickness in Millim. OOOOiOlOlOWlOlOOOOlOiOtOlOlOlOlOiCOlOlOlOIOOiOiOlO tOO^CO©)©*©*©?©*©*©*©*©*©*©*©*©* ©*©?©*©*©*©*©*©<©}©*©*©* ■•••••••••• £ • Tj s ::::::::: j if • : : : : : : : : : ; : : ; ;§ :*,«> : : iifllf 0i - rfsS : ' ' S tf -i & • .S^'cSci ri t*. ~ “ 53 O k • fe > : • • • S ' 9 -Q ,© c © © O ^ ' 55 be bo &) fee be bo a § ; bo ; o ; be J 'S ~ £. s - as-ea = = (= = 9crbc<«,9 a © w bo’s n O O ~ .Jh — — < ..-» O .r- e ^ . .r* o OO.Sc«t-i 5 oeirt 5 «* :S£-g •;**:§£ ® 5 | 3 •o-a-o-c * * S S s ,a * a M 2 * ^•aSg.s.s go-Sro « ¥ o © CD S O ,-< 5 ^ p, ,_i © P^ 1 O OrH O 011 0+3>C I 3 0f-^:;^,-=!^ — < s-i e>- O.m c3 cs * Sh sh ^ .H sg es O wco^ico^ooao 18.3 NON-CONDUCTING COVERINGS FOR. STEAM PIPES. 195 5 COQO®i-KO^OCO«M! 0010 ^t )'10 00 hOSC 500QOO OCDQ 0 « 10 CC? 0 i>^ 10 « 000 C 0 C 005 Hi>t-OQ 05 C 5 O 0 >G 0 H eSCl5M^Tjil010lOJ>000®OOOOrtHiON(Ni>QOW«OW HHr-IHHr-lT-1r-(Hr-l(NWWCOK)SO05COrr^'^TtUD©i>i> O©^J>^i0«Q0O^C0?DWiHf'!©O«0100{>OC0i>l0i> O O O C M O lO 'O ^ Q 00 M 05 rn 00 iO CO - QO CO 05 O? (?i i'^OQOOrHWC'fOOONt-OiM^OOCOOnOOQO'MCO CO 00 CO CO CO ^ ©ft "^T 1 O lO £" £■• 00 00 00 00 Q i-i i-H CO CO ® © OS C 5 WOa^OO^WaOHMHi^iXXMMOOlCCOOHOTHrHO r-I^T-losOlOCO^oduOlOOOQOTjHO^lOOOOOcJoOOO?— 'COCO TH rH t— ( 07 CO -rH Oi CO CO CO O 07 CO 1 C lO 07 ^ lO'HNH^HlC'^COlOCiOW^C'MCQOCOriQO ww^cw C«CON^O)10^^100J>CiiCCOlOi>«OCJTrOOi>i.'^TH THNHCKMCiTHOJlCrtJO^CJCiCJlNCJrHCOlOOCONWWCl i> t-i 07 07 05 OS 00 07 OJCOJ>t'COO?COCO©HC 5 THOO^COrHi>rHi>Ht-COOQOCO COOO'<#COiO('QOt-QOO©Ci©i>© 0 }Mi> NO tH H 07 rH CO 07 t> H O Q QO C 5 GO Q H 07 r— I t— I CO i— I Ph a . _ o U 02 o -© * ^ O - • o cs .03 bC £ ■« '* .5 ® r-“ g -5 — SbS S)1 S * a s S a a ©~ W OS'tH O o « O « ffl 02 <£i 02 O e*i e3 cj> - £■ ©S' j§’ a"'© . ^ ej “ !© fe S . 02 ■© P £ <32 © II «5 02 C « 8;© -© ^ ^ § g.g 1 £ ££ S H O > O C5 E> ft O Ck ei “© cj t 3 © 02 © rrt 02 o© o «© © W © N 1/5 02 -►s 2 73 r© r n © © 73 © ®o I 8° ® .3 *H 02 x © © fl « 03 O'rt^ Kw^Ph c a ^* 3 . . g S2 W JT*'© O „ 0/ a a isfi.2 s <3 “_-°. I 111" g »3 -5 *s o © x © r Jj © -r , qu h <1 u £3 <5 £ O) © II fH rO © C5 00 S 0,-l< ^ NocoNdooo«^a*ioc;o ^i>t-«WIOQO»OOH 01 ^HOOOOOCOOOC 500 H 05 HOOt''®-HC< i-H 1— 1 rl - 1-1 nrl Hrl t-It-i t— I t-I — Tf t-I r— ,-t TH^»O^CSC 9 '^i>r)H'^J>i>iC'r-QOiO'«^lOO-'?T-iT-l«C)COC 5 '^OOi>l 0100 -+i C 5 COio®o^o)f-HOi>ooa!>o::t-®aco.r. c-JCi>CT- oococo (MOlONOWOlOOOH^ffiOliOrtWMmTtUOt-OOC'H'QOOOOW^ THTHWCOMTtUCTHWCCWWNOJWWWNNwWMNMNCICO^TJXeO ^ © a OCOJ>IO«^HOOOrlOOHtD^I> 350 COTHHOOLO(MO?D^WH HHrHOjHCOlOHWrH^OrHQOlOOOlOO'^COWiOlMQOOOlO^iCCO o C gfl O. ui tX) ICJOlOlCiriOlOQOQOOCiGOOOOOQO— 'HHH tHHH- ihh-H lOiOlOiOiOlOiCiCiCiOiOiClOiCMMMMCOmWWOOCOO: • O O CO CO • i> Tt< OOJ>rt!iCCOi>— | 00 iCi- l J> 00 l 0 ljr 5 ^- l '>^ 0005 OG 0 OC 0 l 0 OJ>C 0 ■f§ fs IOO®C5(X)?>®lCHOIOMOQO»OOMCOffiOf-00«rH T-ii-i«COrHlOt-rHX"©nCO«!>®WOTHIO'^WC(N^W t-I Hrlrl N r-l O O i>© 1 C Id 00 1 C C5 t- Ttl OOOOOlOOOlOlCIOIOiOQOiOiOlOlfllOlOlOlfllOiOlOi'MOiCiOlOiO XOrJiCOCMOiT-ii— iXOC'iOXCQC . TJ . c/s. a - d - a. bo bo a -•fg= 2 g £ ' : £ §: as 1 ° S a ■ 25 o - o '5 - .b E <1 NON-CONDUCTING COVERINGS FOR STEAM PIPES, ®oooo^o«o®©rHoiot-ooio^a®Hco^coo ®{^OOCOiCOO«COlOi>i>CMOCOHOr-C5CiOX)rH MiOONWNW^IO^^nffJC'fKOiHKiXNOOOM HMl'HHTTHi-IHHHCgCfflWCOCO^r-C-tWMffit' ^ff}IO«rtO®MO^® 0 ®t-IOrHOOO®®«®t- «C®C'llC 0100 ©OCOlOrHMffii>MT)'®OWOJQ®W !>«DWWTf'IOt-®HfflN©®®t-«TfOJOO»OCOO}® MOiCaOOCOTHCOCO-^CC-^tiOCCOCOt-'OOODCO'^r-ilOOOixrs 35 C 0 HM 05 OOTt'OOWCQ^i>J>WH®MM®HO rHOCDOJ^QOtDQlOCOHiOW-HODTfHMioooOWiOOQO® t-,io Ot 05 th HMiOlOnWM CO Oi CO CO ^ i>MO®e®H^^Tf(Tt<®W'f(r!^icr®®o 5 «ow T-Hi-iCOwETHejo? OWW(.'©MMOWTf<^ 0000 ©«i>'^ 00 {>®COC:W T-iGOO T-lCJT-i 05 CCT-l 05 C 5 '^'^^:Ca 005 xr£>C 5 i >0 lOlOlOWWiOIOClOIOWJOlOWlCWlOlOlOOJOlOlOlO 0*0?0i0j050?©505 05 05©50>0t0i0j0i05c5c50i0505 0*0i © > m > o o 5 g a - bo W a> o p ~ ‘o i= g J ® S '5 H Cj a,Q £ 15 ^ 3 73 -- -o c l-se ° _« ' M CD - So* “ a a © 1=1 - c - .o f- o 3 o T3 CD m w 03 ® ft n 02 T 3 ^ © S3 7 . m r T^ O O ° ^ I * * 2 .. •Sr id. © BQ © f- © © O O O -t - 9 .i: oi © 3 J'O — o £ ^ „„ a> _ 3 03 M ® a a 2 s a •c a Oh O fe O fa d, < O CLO-MO 50 20 23 21 17 21 22 27 10 29 10 11 28 13 25 fj 14 31 34 6 8 51 38 9 19 33 7 37 32 35 15 42 18 43 40 54 48 49 45 46 44 41 55 47 53 52 NON-CONDUCTING COVERINGS FOR STEAM PIPES. TABLE VII. Per cent. Solid Matter. Kilo-Cent. Heat Units. Air space 0.0 1302 a French cotton 0.9 299 b Carded cotton 1.0 310 c French cotton 1.9 299 d Carded cotton 2.0 281 e Feathers 2.0 321 f Wool 2.1 301 g Calcined magnesia 2.3 335 h Wool 3.1 279 i Cork charcoal, coarse. 3.1 343 j French cotton 4.1 248 k Wool 4.3 253 l Calcined magnesia 4.9 340 m Feathers 5.0 262 n Cork charcoal, fine 5.3 324 0 Wool 5.6 220 V Lampblack 5.6 266 q Carbonate magnesia 6.0 371 r Fossil meal .... 6.0 393 s Wool 6.9 224 t Wool 7.9 238 u Asbestos 8.1 1329 V Zinc white 8.8 466 w Wool 9.0 246 X Hair felt 9.2 293 y Carbonate magnesia 9.4 387 z Wool 9.7 237 A Fossil meal 11.2 426 B Pine charcoal 11.9 376 G Carbonate magnesia 15.0 416 D Hair felt 18.5 277 E Omahalite, coarse 18.7 777 F Lampblack 24.4 286 G Omahalite, fine 24.7 823 H Chalk 25.3 560 I Plumbago 26.1 1922 J Calcined magnesia 28.5 1156 K Zinc white 32.3 1164 L Pumice stone 34.2 845 M Plymouth sand 35.6 861 N Plaster Paris 36.8 839 O Barium sulphate 38.1 729 P Common salt 48.0 1983 Q Anthracite coal 50.6 968 it Fine sand 51.4 1690 s Coarse sand 52.9 1684 T APPENDIX. A few years since a very exhaustive investigation was made at the instance of the Boston Manufacturers’ Mutual Fire Insurance Company, by Prof. John M. Ordway, now of Tulare University, New Orleans, but at that time of the Massachusetts Institute of Technology, upon the non-lieat-conducting properties of various materials, some of which may be used for covering steam pipes and boilers ; while others, owing to their liability either to become car- bonized or to take fire, should not be directly applied to such use. There are, however, other problems in preventing either the escape of heat or the ignition of wood- work by the impact of heat, for which purposes various substances are of use. It should not be assumed that because a given material is incombustible it is there- fore not a quick conductor of heat. Neither should it be assumed that because a material is a quick conductor of heat it may not be made use of, in some cases, for protection against fire. For instance, in the problem of making a fire-door. If the door be made of two thicknesses of solid wood at right angles to each other to prevent warping, this door may be encased in sheet-iron or tinned plates with the joints carefully locked, and it will become a good fire stop, although both the sheet-iron and the tin-plate are good conductors of heat. The reason of this is, that while the wood, which is in immediate contact with the metal, will be car- bonized, yet even the sheets of hot metal, if thoroughly locked, and therefore thoroughly encasing the wood, keep out the oxygen ; then, for want of sufficient air to ignite the carbonized wood, the door remains solid and strong for many hours. Thin plates of tinned iron or steel serve this purpose, where thick plates would warp or bend under heat so as to fail in keeping the door- way tightly closed. Iron doors and shutters are often worse than use- less, owing to this tendency to warp or bend, opening a way for fire while obstructing the firemen ; also because when heated they do not serve as a guard near which firemen may protect adjacent wood- work. Zinc, although frequently used, is worthless as a fire stop because of its very low melting point. If a door is tinned on one side only, it may be burned nearly as quickly as if there were no tin upon it, although it may not be ignited quite so soon. 1986 APPENDIX. In order that the relative merits of the different substances which are in use for preventing the escape of heat from boilers and steam pipes, or as substitutes for wire lathing and plastering, or for tin-plates in the protection of elevator shafts, or of wood- work nailed closely to walls, the following tables and extracts from a later report made by Professor Ordway are submitted. It will be observed that several of the incombustible materials are nearly as efficient as wool, cotton, and feathers, with which they may be compared in the following table. The materials which may be con- sidered wholly free from the danger of being carbonized or ignited by slow contact with pipes or boilers are printed in roman type. Those which are more or less liable to be carbonized are printed in italics. Professor Ordway’s report is as follows : “ Careful experiments have been made with various non-conductors, each used in a mass one inch thick, placed on a flat surface of iron kept heated by steam to three hundred and ten degrees Fahrenheit. The follow- ing table, with which the graphical lines correspond, gives the amount of heat transmitted per hour through each kind of non- conductor one inch thick, reckoned in pounds of water heated ten degrees Fahrenheit, the unit of area being one square foot of covering.” Substance 1 Inch Thick. Heat applied 310° F. Pounds of Water Heated 10° F. per Hour, Through 1 Square Foot. Solid Matter in 1 Square Foot 1 Inch Thick. Parts in 1000. Air Included. Parts in 1000. 1. Loose Wool 8.1 56 944 2. Live Geese Feathers 9.6 50 950 3. Carded Cotton 10.4 20 980 4. Hair Felt 10.3 185 815 5. Loose Lamp-black 9.8 56 944 6. Compressed Lamp-black 10.6 244 756 7. Cork Charcoal 11.9 53 947 8. White Pine Charcoal 13.9 119 881 9. Anthracite Coal Ponder 35.7 506 494 10. Loose Calcined Magnesia 12.4 23 977 11. Compressed Calcined Magnesia 42.6 285 715 12 Lio-ht Carbonate of Magnesia 13.7 60 940 13. Compressed Carbonate of Magnesia. 15.4 150 850 14. Loose Fossil Meal 14.5 60 940 15. Crowded Fossil Meal 15.7 112 888 16. Ground Chalk (Paris White) 20.6 253 747 17. Dry Plaster of Paris 30.9 368 632 18. Fine Asbestos 49.0 81 919 19. Air Alone 48.0 0 1000 20. Sand 62.1 529 471 APPENDIX. 198c The first column of figures of results, therefore, gives the loss by the measure of pounds of water heated ten degrees. The second column gives the amount of solid matter in the mass one incli thick. The third column gives the amount or bulk of included or entrapped air. In the graphical table, the value of the non-con- ducting material is, therefore, in inverse proportion to the length of the line, the short lines showing but a small amount of trans- mitted heat ; the long lines showing the larger amounts. There are some mixtures of two materials which may be quite safe, although consisting in part of substances which may be car- bonized. It must also be considered that a covering for a steam pipe or boiler should have some strength or elasticity, so that, when even put on loosely and holding a great deal of entrapped air, it may not be converted into a solid condition by the constant jar of the building, then becoming rather a quick conductor. This warning may be applied especially to what is called “ slag wool,” which consists of short, very fine threads of what may be con- sidered in this report as a brittle kind of glass. The substances given in the following table were actually tried as coverings for two-inch steam-pipe, but, for convenience of com- parison, the results have been reduced by calculation to the same terms as in the foregoing table. COVERING. iPounds of Water Heated 10° F. per Hoar, by 1 Sq. Ft. 21. Best Slag Wool 13.0 22. Paper U.o 21.0 23. Blotting Paper wound tight 2 If,. Asbestos Paper wound tight 21.7 25. Cork strips bound on H.6 18.0 26. Straw Pope wound spirally 27. Loose Rice Chaff 18.7 28. Paste of Fossil Meal with Hair 16.7 29. Paste of Fossil Meal with Asbestos 22.0 80. Loose Bituminous Coal Ashes 21.0 31. Loose Anthracite Coal Ashes 27.0 32. Paste of Clay and Vegetable Fiber 30.9 Later experiments, not yet published, have given results for still air which differ little from those of Nos. 3, 4, and 6. In fact, the bulk of matter in the best non-conductors is relatively too small to have any specific effect, except to entrap the air and keep it stag- nant. These substances keep the air still by virtue of the rough- ness of their fibers or particles. The asbestos of 18 had smooth 198 d APPENDIX, fibers, which could not prevent the air from moving about. Later trials with an asbestos of exceedingly fine fiber have made a some- what better showing, but asbestos is really one of the poorest non- conductors. By reason of its fibrous character, it may be used advantageously to hold together other incombustible substances, but the less the better. Trials have been made of two samples of a “ magnesia covering ” consisting of carbonate of magnesia bonded with a small percentage of good asbestos fiber. One specimen transmitted heat which, reduced to the terms of the first of the above tables, would amount to 15 lbs. ; the denser one gave 20 lbs. The former contained 250 thousandths of solid matter; the latter 396 thousandths. Charcoal, lamp-black, and anthracite coal are virtually the same substance, and Nos. 5, 6, 7, 8, and 9 show that non-conducting power is determined far less by the substance itself than by its mechanical texture. In some cases when a greater quantity of a material is crowded into the same thickness the non-conducting virtue is somewhat increased, because the included air is thereby rendered more completely fixed. But if the same quantity is com- pressed so as to diminish its thickness, its efficiency is lessened ; for the resistance to the transmission of heat is nearly — though by no means exactly — in proportion to the thickness of the non-con- ductor. Hence, though a great man}^ layers of paper — as in No. 23 — prove to be a tolerably good retainer of heat, one or two layers are of exceedingly little service. Any suitable substance which is used to prevent the escape of steam heat should not be less than an inch thick. Any covering should be kept perfectly dry, for not only is water a good carrier of heat, but it has been found in our trials that still water conducts heat about eight times as rapidly as still air. Relative Efficiency of Materials which are used to Diminish the Waste of APPENDIX. 198 e / 3 0^2 P* .T y ^ G e 3 3 y ^ 20 "^Go Qo'OOjOiN^oC'^iOiXDCSOOHOC'iN'aCiNbOOOCl OOC2Q>Qioi<^>^GG;tcio y^l ^ G^ T-I -r — . — I w ’HWW’^-^CPiHN^^NNNr-iCTG) O} GO $| 'O © <5i <55 jy “® <0^3 §•§ § ^ a, y> K *S 5 >">a *■«£ rG ^ ® 111 1 |.g ■ScSS 02 rj © .5 gZ .5? a ca **-* « H © ~ 5 «■ ts S CD © 2.5 b «*-* i-jisl s S 02 © « © g ^ ^ C T2 0^3 — « <0 ‘5 © pQ © ’o2 02 s- 02 $ ‘S S e3 03 jj u/ o sii § § © S ® ® ,S ih © q.-»j S, © •^3 ^ 02 r'Gl -02 ^ e § § .5P 5 § © r 2£ *02 — .Oj ~ *3 © TO 1 § o P -5 12 02 J2 si 02 .^•S 5 S S 02 ■=> y ! 3 © ci S «- %. o ® 5 'C5 °® ! s S « © ^ ^ |> &i ?S — © _« gs 00 (J, ^ <0 cqCL^ox! _ 3§> fc»5 -£Q*^ — - * _2 02 GG "b S3 02 ^3 „, S3 © s3 , — i CD O ci © © O > ^3% 2 ® a i-s s III 3 i *0 © © © 02 O. *j C C 02 O O oi -2 J cu C3CO^lCGOl-QOCiO _o © s 3 01 12 098496828