The air in the smoking-car of the Stonington steamboat train, on the Boston and Providence Railroad, was examined at intervals during the journey from Boston to Providence, Friday, December 11, 1874. The train left Boston at 5.30 P.M., reaching Providence at 7.05 P.M. The capacity of the car was about 2,750 cubic feet net. The number of passengers was thirty-seven, of whom eighteen were smoking. This was about the average during the trip. A somewhat similar experiment (but less extended) was made December 9, 1874, on the Watertown branch of the Fitchburg Railroad. The capacity of the car (after deducting the space actually occupied by the passengers) was about 2,350 cubic feet. On several occasions, I made comparative tests for the ammonia present in smoking-cars and passenger-cars. The amounts in the following table are comparative, simply. 66 66 100 . 575 .810 66 after stopping at a 266 6. station,. 11. Providence Railroad steamboat train, taken at same I may remark, that more of the samples have been taken on the Providence Railroad than on any other, simply because it was more convenient of access. Dr. T. W. FISHER. Yours very respectfully, WM. RIPLEY NICHOLS. The first fact noticeable in Prof. Nichols' report is, that the amount of carbonic acid found in cars exceeds considerably the average for public buildings, and is, of course, largely in excess of what would be found in the dwellings of the better classes, or in the open air. In the Report of the State Board of Health, for 1871, an article, by the late Dr. Derby, on "Air, and some of its Impurities," gives the average per cent. for the outer air in this vicinity as .035, and for school-houses as about .140. The Music Hall is set down at .140 after a concert; Municipal Court-room, .120; Globe Theatre, .144; Waiting-room of Public Library, from .136 to .193, etc. The average of Table No. 1 gives the percentage for smoking-cars at .228, the lowest example being .127, and the highest .369. The average of Table No. 2 gives for passengercars a percentage of .232; lowest, .174; highest, .367. The air on the Stonington steamboat-train smoking-car was exceptionally pure, the average being .170. The car was by no means full, and but half were smoking. The smoking cars of the New York express trains, on the Boston & Albany Railroad, would, perhaps, furnish more marked results. These cars will accommodate 70 passengers, and, according to Mr. F. D. Adams, of that road, are usually filled with smokers, who play euchre from Boston to New York, in an atmosphere of dense smoke. The ordinary ventilators are of no use in clearing the car, and wickets in the ends are required to make any impression on it. The tables show also a second fact; viz., that the additional amount of carbonic acid produced by the combustion of a few ounces of tobacco is hardly appreciable. Prof. Nichols estimates that if all the carbon of the tobacco were completely burned to carbonic acid, the carbonic acid formed might amount in weight, at a maximum, to one-quarter more than the amount of tobacco consumed. In actual practice, however, much of the carbon is not burned to carbonic acid, but some is given off in the state of carbonic oxide, and more, probably, in the form of compounds of carbon and hydrogen in matters of the nature of tar. The carbonic acid from this source would not indicate, however, any additional impurities from the lungs and skin, and it may be disregarded. A newspaper paragraph is authority for the statement, that Dr. Otto Krause, of Annaberg, Saxony, has found nine per cent. of carbonic oxide in tobacco-smoke; but this seems a large amount. Let us examine, then, this question of ventilation in another way. The average capacity of a passenger-car is about 2,500 cubic feet of net air-space, excluding that occupied by passengers and furniture. A smoking-car, as arranged with tables, chairs and sofas will accommodate at least 50, and an ordinary car 75 passengers. This gives, in the first case 50, and in the last 33 cubic feet of airspace to each passenger. The amount of air-space and of air per hour to insure proper ventilation has been variously estimated. Army regulations for hospitals and barracks require from 1,000 to 1,500 cubic feet of air, changed hourly, per soldier. The British Royal Commissioners, appointed in 1857, recommend 600 cubic feet of air-space, and 20 feet of air per minute and per man. Ten feet per minute is the lowest estimate suggested in any case. Take 15 feet per minute, then, as an average, and the air in smoking-cars should be changed thoroughly at least every four minutes, and in ordinary cars every three minutes, to insure proper ventilation. It is evident this is never accomplished. It may be useful to insert here a table from a standard French work, by Gen. Morin, on "Heating and Ventilation" (Paris, 1874). I have reduced the metres to feet for convenience' sake. Volume of air necessary to introduce and withdraw hourly for each person, to insure good ventilation. Cubic feet. 6,300 These figures, Gen. Morin states, are based on direct observation, and are not in the least exaggerated. The point at which all sensible odor from effete animal matter disappears is taken as the limit of satisfactory ventilation. This limit is not usually reached while more than .06 per cent. of carbonic acid remains. Dr. R. Angus Smith says, in his "Air and Rain," a work of undoubted authority: "We cannot accept a lower standard of carbonic acid than .06 per cent.; and uniform diffusion being supposed, we cannot preserve our minimum standard of purity with a less delivery of fresh air than 3,000 cubic feet per head per hour!" This limit is also recommended by Pettenkofer. It will be seen how wide of any such standard is the condition of our steam-cars when each passenger has only from 33 to 50 feet of air-space; and air so seldom changed as to leave a percentage of from 0.2 to 0.3 volumes of carbonic acid! The heating and ventilation of cars seem to be inseparable subjects. The monogram of the Baron de Dershau treats. of the former in quite a thorough manner. He mentions only to condemn the various methods in use, such as footwarmers of hot water or hot tiles, hot-water pipes, stoves of porcelain and iron, and iron stoves outside the cars, over which air is conducted to the interior. He concludes that steam alone is adapted to the purpose; and it is impossible not to agree with him, when we think of the dangerous and unmanageable fire-boxes so universally in use with us. Our stoves, besides overheating the air when approaching a redheat, as is often the case, are subject to as great extremes of temperature as a bad case of chills and fever. The heat is also badly diffused in the car, and is of little or no aid to ventilation. Steam-heating is in use on some American railroads, as well as in Russia, Belgium, Germany and Austria. The Baron de Dershau gives a complete description, with plans and specifications, of a system which he has introduced with success in Russia and elsewhere. It consists, briefly, of a special boiler for every eight cars, placed in a small compartment at the end of one of them, and tended from the platform. The steam is conveyed along the roofs in pipes encased in felt, and fed by vertical pipes into heating-tubes along the sides of the car-floor, the water of condensation being returned to the boiler by a pipe beneath the cars. This system seems to have had no special relation to the ventilation of the compartments to which it was applied. This was provided for by an opening in the roof, allowing for a temperate climate 22 and for a cold climate 28 square centimeters of area for each passenger. Air was admitted by ventilators under the eaves, with openings arranged to catch the draught of the moving train. In a car fitted up for the emperor's summer use, air was admitted through wire screens in the floor, and carried up through hollow pillars containing a cooling mixture, being discharged through small ornamental openings in the capitals into the car. Most American cars are now made with the Wagner monitor-roof, with patent pipes and apertures for the exit of foul and heated air, in great number and variety. These are not efficient, however, without provision for the admission of fresh supplies of air from below. Side and end ventilators |