"Little need be said of them, as they fall within the domain of the companies and the public inspector of gas. Under favorable conditions gas-meters will remain in order for ten years or more; and when they become defective they as often favor the consumer, probably, as they do the gas company. Their defects do not often occasion inconvenience; and when they once get out of order they run so wild that their condition is soon detected, when the errors in previous bills should be corrected by estimate of other seasons."
"You haven't mentioned the apparatus (carburetters) for increasing the richness of the gas, which can be applied by the consumer upon his own premises," said the old gentleman.
"There is little need. The burners should be adjusted to the quality of gas furnished. If there were any real gain in this method of enrichment, the gas companies are the parties who could make the most of it: indeed, many of them do to such an extent as can be made profitable. But whenever the temperature of the atmosphere falls, the matter added to the gas is deposited in the pipes, sometimes choking them entirely at the angles. No: arrange your burners and regulators to suit the gas that is furnished, demand of the company that it fulfil the law and the contract in regard to the quality of the gas, and give all gas-improving machines the go-by.[3]
"Light having, perhaps, been sufficiently considered for the present needs, we have now to note the effects of the combustion of gas upon the atmosphere, and through this upon the furnishing of rooms and the health of the persons living therein," said the chemist, again taking up his manuscript. "The usual products from the combustion of common illuminating gas are carbonic acid, sulphuric acid, ammonia and water-vapor. Every burner consuming five cubic feet of gas per hour spoils as much air as two full-grown men: it is therefore evident that the air of a room thus lighted would soon become vitiated if an ample supply of fresh air were not frequently admitted.
"Remember," said he, looking up from the paper, "that nearly the same effects proceed from the combustion of candles and lamps of every kind when a sufficient number of these are burned to give an equal amount of light. Carbonic acid is easily got rid of, for the rooms where gas is burned usually have sufficient ventilation near the floor by means of a register, or even the slight apertures under the doors—together with their frequent opening—to carry off the small quantity emitted by one or two burners. But there are other gases which must have vent at the upper part of the room, while fresh air should be admitted to supply the place of that which is chemically changed."
Returning to his manuscript, he continued: "The burners which give the least light, burning instead with a low, blue flame, form the most carbonic acid and free the most nitrogen. Such are all the burners for heat rather than light. But the formation of sulphuric acid gas may be the same in each. In the yellow flame the carbon particles escape to darken the light colors of the room, not being heated sufficiently to combine with the oxygen. This product of the combustion of gas (free carbon) might be regarded as rather wholesome than otherwise (as its nature is that of an absorbent) were it not the worst kind of dust to breathe—in fact, clogging the lungs to suffocation. In vapor gas—made at low heat—the carbon is in a large degree only mechanically mixed with the hydrogen, and is liable, especially in cold weather, to be deposited in the pipes. This leaves only a very poor, thin gas, mainly hydrogen, which burns with a pale blue flame, as seen in cold spells in winter. High heats and short charges in the retorts of the manufactory give a purer gas and a larger production. Gas made at high heat will reach the consumer in any weather very nearly as rich as when it leaves the gas-holder; for, thus made, the hydrogen and carbon are chemically combined, instead of the hydrogen merely bearing a quantity of carbon-vapor mechanically mixed and liable to deposit with every reduction of temperature. To relieve the atmosphere of the gases and vapors proceeding from combustion is, of course, the purpose of ventilation. The sulphuric acid gas and ammonia will be largely in combination with the water-vapor, which also proceeds from combustion, so that all will be got rid of together. The vaporization of libraries to counteract the excessive dryness (or drying, rather) which causes leather bindings to shrink and to break at the joints, would be of doubtful utility, since it might only serve to carry into the porous leather still more of the gases just mentioned. The action of both sulphuric acid and ammonia is, undoubtedly, to destroy the fibre of leather, so that it crumbles to meal or falls apart in flakes.
"In a very interesting paper read by Professor William R. Nichols of the Massachusetts Institute of Technology before the American Association of Science at its Saratoga meeting in 1879, the results of many analyses of leather bindings were given, showing the presence of the above-named substances in old bindings in many times greater quantity than in new. Still, their presence did not prove them to be the cause of the decay; and Professor Nichols proposes to ascertain the fact by experiments requiring some years for demonstration.
"In the hope of deciding the question with reasonable certainty at once, I have made careful examinations of the books in the three largest libraries of Boston and Cambridge, each differing from the others in age and atmosphere. The bindings of the volumes examined bore their own record in dates and ownership, by which the conditions of their atmosphere in respect to gas and (approximately) to heat were made known for periods varying from current time to over two hundred years. In the Public Library the combined influences of gas, heat and effluvium have wrought upon the leather until many covers were ready to drop to pieces at a touch. The binding showed no more shrinkage than in the other libraries, but in proportion to the time the books had been upon the shelves the decay of the leather was about the same as in the Athenæum. I am informed that many of the most decayed have from time to time been rebound, so that a full comparison cannot be made between this and the others. In the Athenæum less gas has been used, and there is very little effluvium, but the mealy texture of the leather is general among the older tenants of the shelves. Numbers of volumes in the galleries were losing their backs, which were more or less broken off at the joints from the shrinkage and brittleness of the leather. The plan has been proposed of introducing the vapor of water to counteract the effects of dryness upon the bindings. In this library the atmosphere has the usual humidity of that out of doors, being warmed by bringing the outer air in over pipes conveying hot water, while the other libraries have the higher heat of steam-pipes. If, therefore, its atmosphere differs from that of the other libraries in respect to moisture, the variation is in the direction of greater humidity, without any corresponding effect on the preservation of bindings. In fact, proper ventilation and low shelves seem to be the true remedies for these evils, or, rather, the best means of amelioration, since there is no complete antidote to the decay common to all material things. The last condition involves the disuse of galleries and of rooms upon more than one flat, unless the atmosphere in the upper portions of the lower rooms be shut off from the higher, as it should be. Another precaution which might be taken with advantage is to use the higher shelves for cloth bindings.
"In the Harvard College Library no gas has ever been used, nor any other artificial illuminator to much extent. Neither had any large number of the volumes been exposed to the products of gas-combustion, except for a brief time before they were placed here. The bindings in this library showed very little crumbling, but many covers were breaking at the joints from the shrinking which arises from excessive dryness. In common with many other substances, leather yields moisture to the air much more readily than it receives it from that medium. Cloth bindings showed no decay at all here—very little in any of the libraries, except in the loss of color. It should be stated that the volumes which I examined at Harvard College were generally older than those inspected in the other libraries. There are parchment bindings in each of the libraries hundreds of years old, apparently just as perfect in texture as when first placed upon the shelves of the original owner. The parchment was often worn through at the angles, but there was no breakage from shrinking, the material having been shrunken as much as possible when prepared from the skin. At Harvard College I examined an embossed calf binding stretched on wooden sides which was above a hundred years old. It was in almost perfect preservation, and not much shrunken. This volume, being very large, was on a shelf next the ground floor—a position which it had probably held ever since the erection of the building.
"Professor Nichols does not mention morocco in his tables of analyses. Indeed, morocco was so little used for bookbindings until within about thirty years that it affords a less ample field for investigation than any other of the leathers now in common use. My attention was therefore directed specially to this material, of which I found some specimens having a record of nearly fifty years. My observation was, that in all the libraries these were less affected by decay, in proportion to their age, than other leathers. In Harvard College Library the best Turkey morocco, with forty years of exposure, showed no injury except from chafing. The outer integument was often worn away, exposing the texture of the skin, which was still of strong fibre. In the Athenæum, on the contrary, many of the moroccos showed the same decay as the calf, russia and sheep. There was, however, a wide difference in the condition of moroccos of the same age—some showing as much decay as the calf, while others had scarcely any of the disintegration common to the older calf bindings. The same might, indeed, be said of all leathers, those tanned by the quick modern methods, with much more acid than is used in old processes, in which time is a large factor, showing always a more rapid deterioration. But, the methods being the same, morocco, the oiliest of the common leathers and the one having the firmest cuticle, endures the best.